I believe that the Ryan Plan had some kind of pools for those who don't stay on the old medicare plan, but these pools seem to be based on state laws. These would be smaller than the national medicare pool, but would potentially have the cost advantage (depending on what each state does) of not having to follow Obamacare's one-size-fits-all coverage and Kathleen Sebelius's thousands of pages of regulations that she is still writing.
But it won't become law.
As far as I know Obama-care did not totally replace medicare, there are some changes and cuts for those over 65 but they are not nearly as dramatic as the Obama-care changes to those under 65, Basic Medicare is already single payer, you cant get that much more regulated than it is.
But those in that first ‘pool’ that were born in that year 1956 would have it pretty tough because they would be alone. My proof? Because Ryan is going to those born in 1955 and before and say “you should support this reform because you are exempt from it.” just like Obama-care exempts some politically. If Obama's current plans for medicare are so much worse, why is the voting carrot to those born earlier that they will stay in it?