What I think will be most interesting is to see how the anchored putter guys handle the rule change. Will they wait until 2016 or make the switch immediately. Will also be interesting to see how the change affects their scores. Some guys used a traditional putting stroke first so they will be more comfortable going back to it, but I'd think guys like Bradley will have a tougher time making the switch.
If I were them, I'd do this:
2013 - Putt with my belly putter. Occasionally mess around with short putter.
2014 - Putt with my belly putter. Mess around during off-season and off weeks with short putter. Maybe pull out the short putter for an event or three at the end of the year (fall series stuff).
2015 - Putt with belly putter and short putter in PGA Tour events, moving more towards the short putter as the year went on.
2016 - Short putter! :)