I think this is going to be the most fascinating dynamic, politically.  Trump has "vowed" (for all that's worth) to preserve SS and Medicare.  Will this lead to a cataclysmic clash with Ryan?  Trump does not shy away from such clashes.  Or, will Trump wind up being a tool for Ryan et al. to get their way.

Outside of the politics of this, however, is that a great many Americans will lose.