Maybe kick the can down the road a bit, if its possible? Move the Foundation coins to a time locked contract, spendable after certain day and/or require softfork? If not moved within certain amount of days/blocks -> destroy/redistribute/whatever.
Theres some neat technologies being built and getting realeases in the not-so-far-distant future, so could be useful to have the foundation coins for some use cases which might come available later. From what I understand, sidechains / drivechains will bring a lot of new possibilities for distribution mechanisms and other logics