The long and the short is that they talked to the core nations and it was said there's no appetite for change among most of the nations. Rumours were 7 for keep, 3 for change (Kiwis, Saffas, Argies) among the big 10, then the next teir was split, with the Pacific Nations wanting change, but Japan, Canada, the States and the Europeans content.
The logical move is to move to a more soccer like system. Perhaps not as Draconian, but say instead:
When you play for a Senior Mens first International side, you are locked into that side.
When you play for The Senior Sevens national side, The U20s National side or up to 3 other nominated sides (Can be age graded, Senior, Sevens or 15s, but cannot include U18s or lower) you cannot gain new eligibility based on residency.
E.g. I suddenly become an amazing player. I represent Australia in Sevens. I can still choose to play senior XVs for the Scottish International side, but I could not spend 3 years in Japan and play for them instead.