I'd say you're off on that much shift to Paul.
This is not my belief, it is based in actual inside info. The remaining Newt supporters, (about 5%) are “Anybody but Romney hold outs” who refuse to support Santorum, so they will likely go to Paul if Newt has to drop out. Most of the Newt supporters who wanted Newt because they thought he had the best chance to beat Obama, have already left Newt, favoring Romney with a few going to Santo.
When you think about it, this explanation makes the most logical sense.