“Time passes and love fades.” So sums up IBM’s Watson supercomputer the themes of Bob Dylan’s lyrics in a current ad for Big Blue. “Sounds about right,” the 74-year-old Dylan responds with a wry smile.

It certainly strikes a chord with Baby Boomers, who also swore by Pete Townshend’s declaration that they hoped they’d die before they get old. Well, for those of us still around, too late for that. Especially since the song whence those lyrics come, “My Generation,” was actually released as a single 50 years ago next week.

Also in 1965, Frank Sinatra released the September of My Years album on the occasion of his 50th birthday. Most poignant was the single “It Was a Very Good Year,” a look back over Old Blue Eyes’ life up until then, which he compared to a vintage wine. And 50 years on, 2015 is the centenary of Sinatra’s birth.

Time indeed passes. Still, a half century seems an almost incomprehensibly long span, especially in terms of investments where long term is considered in terms of weeks or months and not years.

But the British government defied the prevailing short-term mindset by selling 50-year bonds Tuesday. For the offering of some 4.75 billion pounds ($7.35 billion) of the ultra-long gilts, the U.K. Debt Management Office received a record £21.9 billion in orders. The bonds with a 2.5% coupon were sold at a price of 98.403 to yield 2.557% at maturity in 2065.

For those with a truly long-term perspective, that compares with a low yield of 2.25% paid on U.K. perpetual consols in 1894. That was when sterling was backed by gold and Queen Victoria ruled the Empire on which the sun never set.

Great Britain’s example should be obvious. There is strong demand for ultra-long, high-quality assets from institutional investors that need to match very long-term liabilities. But, unlike the U.K. government, the U.S. Treasury has chosen not to take advantage of historically low interest rates to lock in borrowing costs for decades to come—as have corporations and American homeowners.

The U.S. Treasury has mulled issuance of 50-year bonds—as opposed to 30 years, its lengthiest maturity—but has resisted that option. In mid-2014, the Treasury was reported to have polled the so-called primary dealers—those with which the Federal Reserve conducts open-market operations and also are expected to bid at Treasury securities auctions—but wasn’t ready to pull the trigger. Which raises the question, if not now, when?

Speaking at the Barron’s Art of Successful Investing conference Monday, Jeffrey Gundlach, DoubleLine chief executive and chief investment officer, opined that bond yields “broadly bottomed” when the benchmark 10-year Treasury hit 1.38% in July 2012. Since that time, the 30-year bond also hit a record-low yield of 2.25% early this year and remains below 3%.

Not that Gundlach sees the sharp rise in yields predicted seemingly forever by bond bears. But several years down the line, some of the salubrious factors that have kept interest rates low will be reversing.

While every corporate treasurer has taken advantage of subdued borrowing costs to extend maturities, Gundlach said “hundreds of billions” of dollars of high-yield bonds, leveraged loans and investment-grade corporate bonds will be coming due around 2019. At the same time, the Fed’s holdings of Treasuries will begin to mature as well. That adds up to a massive supply of bonds for the market to absorb.

Starting around the same time, the federal deficit—which has shrunk substantially, to only about 2.5% of gross domestic product—will be become problematic again. As the retirement of those Baby Boomers accelerates, the Congressional Budget Office forecasts entitlement spending will shoot up in “hockey stick” fashion, he added. Indeed, entitlement spending and the budget could be the big issues of the 2020 election, Gundlach further opined.

Given that borrowing costs now hover near historic lows, investor demand for long-dated fixed-income assets is robust and borrowers are tapping the market to exploit attractive financing options rather than out of necessity, shouldn’t the U.S. Treasury do the same?

To be sure, Uncle Sam has been able to borrow recently for absolute zero by issuing short-term Treasury bills. Indeed, notes due in three years or less cost the government less than 1%. So why borrow 50 years if it will surely cost well north of 3%?

If Gundlach is right, locking in a sub-4% borrowing cost into the second half of the 21st century will look like a good deal for taxpayers, or more particularly, their children.

The Treasury, however, has been reluctant to innovate. During the 1980s, with long-term interest rates at historic highs, the department emphasized long-term, fixed-rate, non-callable debt. As a result, U.S. taxpayers locked in high borrowing costs. It’s not so long ago that the last 30-year bond with a double-digit coupon finally matured. Meanwhile, innovations such inflation-indexed and floating-rate notes weren’t introduced until much later.

By contrast, the U.K. Treasury embraced alternatives such as inflation-indexed bonds long before. It even issued floating-rate, U.S.-dollar-denominated securities—not long before the 1985 Plaza Accord paved the way for a lower greenback and interest rates.

Mexico also issued 100-year bonds—denominated in euros—earlier this year. That is indeed a vote of confidence that the Mexican government will be there to honor that obligation. As for the euro still being in existence in 2115, who knows? For that uncertainty, investors were rewarded with a 4.2% yield when the bonds were sold in April.

As IBM’s Watson observed of Dylan’s lyrics, time definitely passes. As it does, opportunities can slip away.
 
Rather than fighting over things such as the debt ceiling, Washington would do better to deal with its financing options now—while interest rates are at historic lows and before the real fiscal crunch begins later this decade.