If Ryan was the least bit serious he would propose changes to medicare starting now (like the dual system he now proposes) and then setup some metrics so we can see how its working over the years,
... because as you pointed out, there is no guarantee that insurance companies will turn out any cheaper than government price controls for seniors health care, given the same care.
I suggested this back in early 2011 when he first started on the idea.
But his 10-11 year delay before doing anything is a cheap political gimmick that never worked (to convince anyone) and it never will work. Its so obvious.
I concluded long ago that Ryan is not the least bit serious about this issue (hell he voted to expand Medicare benefits under GWB), this resolution is just for the gullible.
The Dems will make fun of it as it is full of holes and like a dog whistle the gullible will get the idea that it is brilliant, while they pass the CR funding Obama-care.