The Russian speakers in the Baltic countries are a valuable resource, a window into a Great Power destined to play a great role in Europe in the 21st Century as it has ever since Peter the Great. And while Estonia may have legitimate historical grievances against Russia and Russian speakers, this should not get in the way of the pragmatism that is otherwise such a valuable part of the national character. Russian language skills are very useful to have.
So is Estonian, if you want to get anywhere in Estonia these days. The incentive to learn Estonian is certainly there for the Russian population of Estonia. The only reason they might not want to learn it is because of pride. Russians, indeed, most human beings, have a tendency to respond to obtrusion with obstinance. The more they feel that they are being forced to learn Estonian, the less they will want to. But the sooner Estonia will grant them full citizenship, the sooner it can start to benefit from them.