Here is the newest info on accessibility changes to the Tube system.
Transport for London is continuing to roll out support for contactless bank cards for fare payment. Here’s the link for the latest on this topic. Although the website says that Amex has contactless cards, I rather think these must be issued at high annual fee levels in the USA. American Visa and MasterCard may not have this option so may not work. No problem; I’ll be sticking with my Oyster card.