I got LT points on a test run of 1K United points.

If you are willing to buy retail and sell wholesale, you can move Marriot-to-SPG-to-Marriott and get LT credit for 50K.

I guess the question is whether combining lifetime activity in August retroactively counts towards the legacy requirements of Marriott Rewards.

I have 750 Marriott nights and 1.75 million Marriott points.
I have a small number of Starwood nights (<200), but probably have around 500,000 LT Starwood points, primarily from the Amex.

Is that LTPP by itself? (I don't have 10 years of Platinum.)

I've been led to believe, so far, that it is not enough. I need 2.0MM Marriott points by July 31.

If my transfers via my wife work (in conjunction with redeeming an award), I won't have any hard costs to get to 2.0MM, so I'll go for it just to be sure. But if we interpret the rules as loosely as possible, then there are going to be a ton of LTPP's out there on January 1.

Does all United-to-Marriott transfer activity require Premier status on United?

My understanding is unfortunately, no. I'm reading it as you can qualify with either 750 nights + 2 million points with the legacy Marriott rules, or 750 nights and 10 years Platinum with Marriott + Starwood.

Yes, Premier Silver or higher, which includes Marriott plats.

That's actually my understanding as well. Get to 2 million points in July. That's my "sure" path.

I think I've been MR Plat for about 4 or 5 total years and SPG Plat for 3 and change. The SPG Plat years were also Marriott Plat years. I truly have no idea how this is counted, whether I have 4, 5, 8, or even 9 total years. (I'm just assuming it's less than 10.) If I was sure I was on 9, then maybe I'd have until December 31 to complete Plat in the combined program? That part is confusing - I'm just going to get my points by July. :)

Please keep us posted.

In the FAQ it says the years is based on the night qualification of status, so years of the 50-night status will be that with the combination and going forward.

Making it on nights
 

I wonder whether this means that for some SPG elites, years of Plat earned on the basis of 25 stays rather than 50 nights won't count as Plat years.

It is my understanding that they will run the LTPP qualification through their computer twice. The first time will be in August, 2018, then a second time on an unspecified date in January, 2019.

The main advantages I can see on making the cut in August would be the peace of mind that it is done and over with, and you will have a few months to fix any problems if something doesn't compute right.

There is a much lower probability that if someone is LTG in MR in August, and then earned LTP in MR before 12/31/18, they would be platinum in the new program for a few months until the second round of processing occurs in January. But I don't think that would apply for most people. Even if it did, there isn't a huge difference between Platinum and Platinum Premier in the new program anyway.

Personally, if I were in this situation, I would also want to get LTPP nailed down in August so I would try if at all possible to complete requirements in time even to fix stuff if everything hasn't posted by the last week of July.

This. My husband could easily reach the 2MM points by Dec 31, not so easy by Aug 1 (he's already met the 750+ nights and it's just points that he needs). So he'll be applying for the new credit card shortly to try to add the 100k bonus to his balance by Aug 1. Combined with his stays for the next 3 months, he'll reach LTPP by July 31.
I know Marriott has changed their tune since the original announcement, but it still makes me nervous to wait until 12/31. They're making so many changes and having so many IT problems. We just want to get it done.