Probably doesn't matter anymore- but I'll offer my data point anyway. Was away from FT and having never flown AS didn't think to come check the boards to see if this was an issue.

I have VX Elevate Silver. This was status matched from AA PLT (which also matched to JB Mosiac) but I flew F LAX-BOS last May. That was my only VX flight and I wanted to compare it to JB Mint on BOS-LAX (Mint FTW). I had the miles in my elevate for that flight, and nothing else.

I received the email from AS last week I think. IIRC, the jist was that I could have bonus miles in my AS account if I linked the accounts. I feel like it mentioned being able to create my AS account at that point.

Created my AS account, linked it to my VX account and miles were there within minutes. As I don't foresee myself choosing VX over JB for that route before the merger is complete, I also transferred my elevate miles into AS. Took only minutes as well. VX Silver matched to AS MVP.

Probably will be flying AS this year in the fall; not sure if they fly the route I'm thinking of, but next year actually planning a trip to SEA so will fly them for sure then.