Not quite dead no. Since none of the usual suspects are giving you a reply, I'll give you my educated guess.
The whole point of the kin/balance build is to pick up force in balance for use while running in combat technique. Picking up force in balance gives a shadow a very high damage aoe that can be used out to 30 m. This greatly improves versatility. Since FiB is only on the 3rd rung of the tree, its very accessible to a hybrid.
There's just not a whole lot exciting in the lower rungs of the Infiltration tree that would enhance someone running in combat technique. If you were going to make an infiltration hybrid, you'd pretty much have to spend the majority of your points in the Infiltration tree and run in shadow technique to be worth while. Once you've invested that much into the Infiltration tree, you might as well just commit to full Infiltration.
Don't forget Project with Upheavel can do a bit of damage with their crit/damage boost. Good stuff.