I added links to the relevant FT forums as well as information form the website of each hotel chain.
sdsearch, I added the thread titles to the links you provided.
Hyatt Lifetime Diamond seems a bit murky, but I think that you need to have Diamond for 10 years and earn 1,000,000 base points. However, they don't advertise this perk on their website so I didn't add any more info other than the link to the FT discussion.