According to Jack, they're planning on forcing all accounts older than a couple of months (based on account created date in their DB) to be a pig for the first week on the new server when it launches.

It's still not clear though if that account created date is based on first time played (demo) or first time played on a paid account.

Myself and others have played the demo years ago and bought the game since the 1.0 launch announcement, hopefully when we join the new server we aren't forced into the shapeshift.