I sympathize with your point of view, but this kind of primary would do nothing to change the problem. If non-Romney non-millionaire types are struggling now, how will they fare when they have to run a fifty-state primary campaign all at once?
Simple; eliminate "bundled" Campaign Contributions, and ALL campaign contributions are limited to $2300, per individual, per PAC, per Union, etc.
Take the millions that are collected via bundlers, lobbyists, etc., and limit EACH 501 to a contribution equal to what an individual is limited to. ONLY single $2300 maximum contributions can be made, period.
Then, we have a Primary Election Day, nationwide, where all States select their candidates. Likewise, voter Registration for Party Identification purposes, is for a 2-year mandatory period. No Party switching to vote in opposing Party Primaries.
This will reduce Elitist Candidates, and force expenditures to be focused on each State's interest on local media.