The reason I've diversified away from Marriott and am working on LT Plat with Starwood is because we don't know which hotel chains will treat their LT elites well and which will treat their LT elites poorly 15+ years from now. I'm also concentrating on Hyatt Diamond, hoping that they'll lower their LT Diamond requirements - currently 1 million base points ($200K hotel spend prior to taxes).
Marriott LT Plat is in the bag; I need less than 90K points to hit 2 million MR points.

You are putting all of your eggs in one basket; I recommend that you diversify IF you have the chance to do so (your company may mandate staying at Marriotts). Starwood is easy to achieve Plat; 25 stays or 50 nights/yr AND award nights count toward status. 10 years as SPG plat and 500 nights should be easy for you.