I don't think they'll ever have such a button. What I'm doing is auto-forwarding all mail from GApps to my regular Gmail account. And as I added the GApps accou

I don't think they'll ever have such a button. What I'm doing is auto-forwarding all mail from GApps to my regular Gmail account. And as I added the GApps account as an outgoing account/identity in Gmail, I can send/receive from my regular Gmail account, but with it showing the GApps custom domain address in all my emails. If you did this, at least you could still keep your GApps email adress even if you started over with everything else (purchases, etc).