The primary objection to the rule from its opponents—that it would move the brokerage industry to a fee-only compensation model and therefore price low and middle-market retirement savers out of the financial services market—is “unbelievably nonsensical” to Evensky.

“None of those objections hold much substance,” he said. “The brokerage and insurance industries say they want a fiduciary standard, but they are attempting to redefine what a fiduciary is.”

Which is unnecessary at best, and disingenuous at worst, in Evensky’s mind.

“The concept of a fiduciary is simple and it is well-established in the law. It boils down to managing the best interests of your clients. We don’t need a new ‘uniform fiduciary standard’ as the brokerage industry calls. We need to enforce what already exists,” he said.

And that’s what the DOL’s rule does, he thinks.

Those who say the consequence of the rule will be an industry-wide shift to fee-only models think differently, of course.

Secular analysis from ratings agencies has said the DOL rule, as proposed, could significantly impact existing distribution channels for annuities, products sold on commission by insurance agents and broker-dealers.

Non-secular advocates of the insurance products clearly find that prospect troubling.

In 2014, $80 billion worth of fixed-annuity products were sold, about half through IRA accounts, according to data from LIMRA, cited by Kim O’Brien, CEO of Americans for Annuity Protection, in an interview with BenefitsPro.com.

Presuming a best interest standard advanced by the DOL would force commission models to extinction, 401(k) assets’ access to annuitized products could be severely restricted, fears O’Brien and other annuity advocates.

To a growing number of academics and regulators who see annuities as a vital hedge to longevity risk in retirement, that potential outcome would not be in retirement investors’ best interest.

Evensky can be counted as part of an emerging chorus that sees immediate and deferred annuities as not only useful, but necessary tools to retirement strategy going forward.

He did not always think so. As a fee-only fiduciary, Evensky once was as outspokenly critical of annuities as he is now a proponent of them.

“In the next ten years, annuities are going to emerge as vitally important vehicles for retirement planning,” predicts Evensky.

Even today, amid historically low interest rates, Evensky sees a place for annuities in some of his clients’ portfolios. But he expects to be recommending annuities to the majority of his clients in the foreseeable future, even for the wealthiest, who can use annuity strategies to replace existing low-yielding conservative allocations to hedge against longevity and out-of-pocket medical and long-term care costs.

And as interest rates rise, making annuity payments more valuable, their value as a tool to turn assets into retirement income will only compound, he says.

That’s going to test the fiduciary purity of fee-only RIAs, who Evensky says will have a fiduciary obligation to move portions of savings into annuities, even though they will not get paid for doing so, because they cannot accept commission compensation.

On the occasions when Evensky recommends annuitizing portions of savings, that’s business he walks right out the door.

“It’s black and white for us. We give that business away because we don’t get paid on the assets that we recommend to an annuity. That is the reality of being a fiduciary. If the annuity option is in that client’s best interest, I have no choice but to put them in it. Even if it means I lose money,” he explained.

He is so convinced of immediate annuities’ utility, even fiduciary necessity, going forward, that he sees an emerging conflict of interest for fee-only RIAs on the horizon.

“It’s going to be an interesting issue,” he said. “Immediate annuities are going to become an important part of financial planning. Fiduciaries are going to have to recommend products they can’t get paid on if they are to do what’s in their clients’ best interests. It’s just that simple.”

Evensky questions the reasoning that says DOL’s rule will restrict access to annuities. He is, however, confident the rule, as proposed, will change business models.

“That’s fine. The fiduciary standard isn’t written to protect business models, it’s written to protect investors,” he said.

One recent blog post from a financial planner and consultant to advisory firms suggests some fee-only RIAs have found a way to circumvent commission restrictions on annuity recommendations.

In June, CNBC released its top 100 list of fee-only RIA firms.

On his blog, “Nerd’s Eye View,” Michael Kitces took the time to look at the top 10 firms’ Form ADV Part 2 disclosures.

He found “nine of 10 of them share in insurance commissions, own an insurance agency, or are under common ownership alongside an insurance affiliate to which advisory clients are referred,” he wrote.

Kitces was not available to comment on his findings before going to press.

Evensky was.

“Truth? In advertising?” wrote Evensky in an email after reviewing Kitces findings, questioning the integrity of advisors that claim they are fee-only when they are not.

For a purist like Evensky, there’s just no room for commissions in the pocket of a true fiduciary.