I have no interest in this, so please, if a decision is made to provide emails instead of PMs, please make it an option so those of us who prefer PMs can continue that way. I get more than enough emails now, I don't need any from this or any other forum.
I would imagine it would be optional just like post subscriptions are now. There's a space beneath each post that says "E-mail me.." and you can also toggle it to be the default in your profile settings. So if this was implemented I imagine it'd be much the same deal.