I can almost guarantee Roth IRA holders will get screwed in the future. At least 401k holders got a tax break on the front end. Also, most middle class workers have at least something in a 401k, especially since companies are moving towards an opt-out model on 401ks. Relatively few Americans use Roth IRAs and most are "high" income types.

Politically, it will be a slam-dunk to tax the crap out of money coming out of Roth IRAs in the future.