It would seem like, intentional or not, flow would be likely to do two things:
1. It would disproportionately attract those with black marks. One could debate whether or not such things as multiple failed checkrides, no college degree, or multiple DUIs or other run-ins with the law actually do predict your performance as an airline or not, but these (and other) black marks certainly have been used as discriminators, rightly or wrongly. But there is little doubt that those people with such black marks are being ADVISED to go to an AA wholly owned. You see that all the time on APC.
2. It would pull in those risk averse, the ones that are willing to wait a decade for the supposed ‘surge thing’. Again, it’s probably arguable if that is a good or a bad thing in a major airline pilot. But at least in some respects it well might be a negative, particularly when we see regionals with flow (or quasi flow, see Alaska/Horizon), having either to resort to DECs, near-DECs, or forced upgrades because their upgrade eligible FOs won’t bid on the upgrade.

All in all, it would appear that a flow over time would act to concentrate in the regional an increased percentage of people that the major wouldn't have voluntarily recruited OTS.

That makes me wonder if, after eight or nine years of waiting, people aren’t going to see their flow programs abruptly terminated if the major is not contractually bound to that program, and maybe even if they are. The management at the major certainly has more legal horsepower than the unions at most regionals.