No doubt he’ll be announcing his intention to run for office soon.
If he can prove it with DNA any office in Massachusetts not currently held by a Kennedy relative is probably open to him. Those people are real Royalists up there. Birth and rightfulness counts for everything. As Democrats in general tend to that royalist bent the Clintons have taken that position in the general party. Unlucky for them they are just getting going when the Messiah comes along calling for Change!
If he can prove it then he's eligible right now! Let him step in as the 'Rat unity candidate!