If backward time travel is also somehow possible, maybe firms in the future will choose to outsource some of their operations to the past, locating their manufacturing and other services in lower-wage time periods. This opens the possibility of transtemporal gains from trade... assuming, of course, that governments don’t implement effective trade barriers. Would America-3000 place tariffs on goods from America-2000? Would temporal nativists call for the construction of a time-wall to keep out the trans-temporal immigrants -- even if those immigrants were, in fact, their own ancestors?
In the unlikely event this all comes to pass, there would probably be a few other issues that took precedence. But just for fun, how about regulation along these lines: outsourcing of this type would be limited in such a way that it could only be utilized in times of tight employment markets, taking advantage of high unemployment in earlier eras. This way we could finally deal with that pesky Great Depression I'm always reading about.