Now that GM2 is out with a Road Map I'd guess that 1.4 sales will dry up to almost zero.
Add to that that YYGs has announced that 2.0 purchasers will get 1.4 licences, now would be a good time to announce all 1.4 purchases from this day forward will get 2.0 licences.
Given we are still months away from release that's a long time for minimal sales and will create cash flow issues. There is also no point in trying to create some arbirary back date, all that will do is piss off those who are just beyond it.