Term limits would help, but that is not going to keep people from voting in RINO's, nor is it going to resolve the issue that we don't have enough conservatives running.
Yes, it would have kept Mitch from continuing to wreak havoc on the party but in the same light, term limits would also oust people like Cruz, Lee, Paul and others. So there is a trade-off and I'm not so sure that the trade off in the long run would be worth it.
Mitch will eventually get too old to function or pass away. Rather than term limits I think age limits would be more appropriate. Once someone reaches 75, they need to finish out the year and then they are done. They can no longer run for political office, at least at the federal level.
Just my opinion.