Looking at the current policy proposals and programs out there, it looks like there are two main routes - using the feds to set out national guidelines through the NIST and legislation like CEVA, or alternately encouraging states to adopt model legislation that would accomplish the same based on NIST standards also - which are essentially voluntary guidelines regarding best practices, but nothing making them mandatory.
CEVA does try to mandate national standards in regards to voting eligibility, election audits, registration requirements, and other areas, but nothing as to one national ballot or election system for federal elections as far as I can tell. I havent seen any exact proposals for that either. I would not mind it as long as the feds paid for it. But while I would not mind waiting in two lines to vote in two separate elections - federal and state/local, I can imagine many others would and complain about the cost of maintaining separate systems - but such duplication occurs all the time in other areas - especially in regards to taxes. Tax returns are separate, so why not ballots also - which are far simpler than tax returns.