The Wiki states:

If you received a lifetime Club membership from the UA MM program ...........

When did United give lifetime Club membership from the UA MM program ???

You are discounting the time and expense to document and train agents about an exception for a very small number of members which is likely the bigger concern for UA. Further, it sets a precedent of potentially having to make carve-out/exception's whenever there is a change in lounge policy. I wouldn't be surprised if you were to push this legally that they might end up offering some sort of pro-rated refund rather than making policy exceptions.

LT Red Carpet Club membership was for years a benefit of making 2 million miles with the old pre-merger program.

Exactly $20 for every year since effective date, up to $160. A gesture, not a settlement.

Intended to avoid unwanted media exposure.

My guess if you do the equivalent NPV calculation on the purchase of the LT UC membership and the lowest cost of UC membership in the years since the LT purchase has a return value exceeding most investments. And add in the future value ( even if reduced somewhat due to this change) and financial result is even more in the purchaser's advantage.

No one is going to care about a few frequent flyers having their benefits incrementally curtailed. Least of all UA. For one thing, there's no YouTube video ;)

Agree, I don't think that calculation will help the LT members' argument at all.

The law will allow future value damages based on expert testimony. Typically the expert will just a pick date beyond which future value becomes too speculative to estimate. Five years would be pretty common, though obviously the exact number depends on the particular circumstances.

Unwanted media exposure? What media would possibly want to "expose" this? That UA actually wants you to fly on their own planes to use an lounge?

If UA stood its ground in Lagen v United Airlines lifetime million miler suit - with all its ugliness, including the written dissent by a Federal Appeals and then the court affirming they can unilaterally change lifetime benefits which had a lot of media exposure - then they certainly don't care about this.

Delta announced this several months before UA - where is the unwanted media exposure for them? Lagen v UA set precedent at a Federal Appeals Court level - I can't imagine any reputable law firm would remotely entertain this - I can only imagine how money was lost by the Lagen attorneys who probably felt certain UA would settle and divvy up attorney fees.

The court in Lagen punted to Congress. Media exposure may not be a deterrent to a company like UA. Point taken.

The Seventh Circuit affirmed on two grounds - the promise to million milers was not part of the contract with Lagen, and any deceptive practices claim would be preempted by the ADA. The dissenting judge believed UA's conduct to be fraudulent and that there should be a remedy for that. He was outvoted.

Obviously, all dissenting judges are outvoted. All 3 recognized the Act’s preemptive effect. MileagePlus Program rules have always allowed United to tinker with the program and Lagen failed to prove that Million–Miler bennies are/were separate. But the Court cited a 1992 ruling that the ADA “does not give the airlines carte blanche to lie to and deceive consumers." It channels grievances to DOT, the choice Congress made.

Hence the question, does a paid club membership that had no airline ticket requirement fall under the ADA?
And does UA want this to be the test case?
I'd wager that UAs lawyers have been debating this since I raised the issue.

I'd wager more likely than not, UA lawyers haven't debated this whatsoever and haven't even been looped in. My opinion, DL havesn't debated this either and they announced months ago before UA.