I think they only solution is to let their stars play overseas without a cap limit. Free up the wage bill and allow them to blood up and coming players in the regions.
I was listening to the GBR podcast and Foxy was saying that the rest and extra welfare that being centrally contract offered meant that a lot of these players may well end up staying in Wales anyway. He said he took a big pay cut to leave Clermont but it was the best thing for his rugby and himself and family.
The trouble that you are going to have is that making the regions development teams will kill off what little chance they have in the rugby champship and in Europe. Cannot see the crowds flocking to the regions to see them get hammered by the Irish, Scottish and SA teams every week. The plaster that they need to rip off is that they really cannot keep 4 regions and 3 may be pushing it. 2 regions packed with the best that Wales can offer may be a way forward but nobody wants to see half of the Welsh professional players made redundant. Tough situation really but the solution seems to me to be to work out how many teams that you can actually afford to fully and properly fund and go with that and hope that any success that they and the national team have can help bring back more teams in the future.