I don't expect ICS for D3 for sometime. With the D4 coming MOTO will wanna show off that phone with all the bells and whistles. I expect the D3 to get ICS by summer of next year. I hope I'm wrong.
I think its a given that the D4 will come with ICS and that without any major work to port ICS to the d3, it will still take the better part of the year to get it deployed by Moto and Verizon. So your prediction of summer might just be a bit optimistic, but I'd bet you're not far from the mark.