At this point there are no longer any challenges or problems, there is a simple conflict:
While the states themselves are compliant with the RealID Act, a large number of individual people in the US are not compliant, since a number of states will still issue non-compliant IDs if the individual so chooses.

The only way to force all people in the US to be RealID compliant is to mandate the at the states cease issuing non-compliant IDs. Since the feds won't mandate that, there will remain a significant fraction of the traveling public who choose to get non-compliant IDs for some time, which will cause utter chaos if RealID compliant IDs are made mandatory for boarding a plane.

The REAL ID Act doesn’t make it non-compliant for people — myself included — to continue to refuse to get local ID except those which are not REAL ID identification documents. The lingering Covid-19 impact hasn’t come with growing public refusal to get REAL ID identification documents, and I’m sort of disappointed by that.

Just today got hit by some unwanted “get your REAL ID” type notice from some US airline while booking and/or checking in for flights via the airline app. Too bad to see the airlines trying to push this REAL ID thing so much on travelers when it’s not required.

No, RealID is not required yet to get on a plane, but at some point in the future it will be.

And when that happens, those people who choose not to get complaint IDs from the states who offer them the choice will then be forced to undergo egregious violations of their rights - i.e. full body rubdowns with repeated genital contact, plus enhanced chat-downs and other violations to establish their identities - to transit a checkpoint. I firmly believe that this is why the deadline continues to be pushed back, not due to Covid-related delays, but because there are still so many Americans with non-compliant IDs who would not only clog the checkpoints around the country as they undergo their interrogations and physical assaults, but would raise a hew and cry to Congress that might jeopardize some politicians' re-election campaigns.

It's easier to keep kicking the can down the road until those states who still offer non-compliant IDs knuckle under whatever pressure the feds might put on them and stop issuing non-compliant IDs. That could be another ten years, but... government NEVER gets smaller or less intrusive, only bigger and more intrusive. It's a one-way street, and at some point, there will be another law passed, or an amendment to the RealID Act, that prohibits states and territories form issuing non-compliant IDs. After that, it'll be smooth sailing for DHS to require compliant IDs for air travel, and any other purpose they might want to, and the data sharing part of all this will morph the whole thing into a national ID card program.

how likely is this going to be further delayed? My own CA DL is up for renewal and I can get it by mail - the email even indicated that I’d get it by mail before having to pay the fee. Or maybe I’ll get an invoice first and then the DL? It’s not fully certain for me.

I don’t have REAL ID and if I can further delay then that’s appealing. If Real id kicks in then I assume that I can use my passport and tsa pre privileges. Maybe if the government wants real Id then they can require it first with tsa pre / GE / clear. Then maybe everyone would get it in order to continue that joy of trusted traveler programs.

Great, another delay. I'll be renewing my 5 year old CA Real ID in about 6 weeks, almost 2 years before the new deadline.

I just renewed my California Real ID license. It was no different than renewals were before I got my Real ID CDL five years ago.

Passports — and US passport cards — are considered REAL ID compliant. I will continue to avoid going through the hoops to get a REAL ID DL, for our passports and passport cards will continue to be accepted for TSA TDC purposes.

No hoops. It's no different than renewing a DL in person when a new photo is necessary every several renewals, except that I brought with me my passport, Social Security card, a property tax bill and a utility bill (mortgage statements, lease agreement, etc., would have also worked).

Not your mother’s birth certificate or your retirement savings history?

…. for many who have already done it for a REAL ID compliant DL. For me and tens of millions of others, there are additional hoops to do so.

Such as?

The hoop (depends on state requirements on a renewal) would be additional documents other than merely bringing in your current license. Some states may have same documentation requirements even for a renewal.

What I posted earlier in this thread to which GUWonder responded without specifying what their additional hoops were:I did not need to bring or show any of those documents when I renewed my California Real ID license. Neither did my daughter when she moved back to Illinois and had to get her Illinois Rel ID driver's license reissued.

On top of bringing all those documents in Pennsylvania, one must pay a one time $30 fee which I refuse to, since I don't need it. :)

In California, a Real ID driver's license costs exactly the same as a CDL for which "Federal Limits Apply."