So, I think GW wants us to run characters?
Voluds, Draigo and a GMDK supported by 3 squads of Interceptors and the loyal 32 doesn't seem like a bad start to a list.
Yeah, I've been doing a similar mental exercise.
The idea of an elite Grey Knight squad backed by a strong gunline seems so appealing. You might want to include an Apothecary for healing, or a Brother Captain for double distance smite.
Then you think about the fact that these units can deep strike, but they still have less than half a chance to get into combat the turn they arrive. Then you think about the fact those characters and infantry units cost as much as 3 Basilisks and 3 Medusas.
The competitive objective is you could have a lot more Dakka in your army without them. The fluffy objection is these aren't Terminators, it doesn't look like a Grey Knights army.
While I think we will see a couple lists like this turn up at tournaments, I don't think they will do very well.