Even Politifact says: "Attacks on Ryan Medicare proposal named 'lie of the year'"

From The Hill newspaper:

The claim that House Republicans' budget would end Medicare is the "lie of the year," according to the fact-checking website Politifact.
According to Politifact's analysis, saying the Ryan plan "ends Medicare" overlooks the fact that its changes would not affect people 55 and older. Politifact also said Medicare would remain in existence, but in a different form — which Ryan's critics say is the same thing as ending Medicare.
Democrats and liberals slammed the decision and stood by the contention that Rep. Paul Ryan's (R-Wis.) proposal would end Medicare. . . .
"The very definition of the Medicare program is a national health insurance program for seniors which House Republicans would abolish under their budget," the Democratic Congressional Campaign Committee said in an earlier rebuttal of Politifact's analysis of the Ryan plan. . . .

How does Ryan's proposal end national health insurance?