I do not think you have ever heard us say we where never going to support php or mysql
In fact we have addressed most anything brought up thus far as far as compatiblilty
I have not seen any discussion here on html5 or schema.org so can not comment at this time as I have not looked into what your saying although I will do reading on what might be pertinent on for our products.
As far as jquery or the like our application uses lots of jquery ajax features and we update and introduce new features as we can implement them without breaking anything else. Like we introduced Photo Tagging in 8.3. Will our application operate like Facebook no that i know we have said.
Other than that is it all about adding functionality without breaking away with what our application is and the core features.