He's 31 now, does he really have 5 more years in him? Leo Cullen is 34 and is nearing the end of his career. I'd imagine Leinster might compensate Connacht with giving them Fionn Carr (with confidence now destroyed) and Damien Browne back if they're lucky.
I agree it's unfair on Connacht. But that's the reason why the Irish teams are so strong in the Heineken Cup, they basically sacrifice their fourth team and put the vast majority of their resources and top overseas signings into those teams as well. They basically have nearly every professional Irish player still playing in Ireland in just 3 teams. Wales on the otherhand, haven't sacrificed the Dragons quite the same way, and have their strength evenly split between the teams with the Dragons only slightly weaker than the rest. Add to that they've lost a number of players to England and France, whilst France and England have their top players spread out over 9 or 10 teams, thus meaning that the IRFU's policy of sacrificing any chances Connacht have of challenging and keeping nearly all Irish talent (at least which is worth having) at home is the reason for the strength of the big three Irish teams in the H Cup.