Looking at history, they'll just take it for themselves. Does anyone remember when US government seized BTC-e exchange, where BTC-e user never get their BTC back?
Even if they were intentions of releasing the coin to the so called original owners how do they verify their authenticity when they no longer have access to their private keys. If entities with QC supremacy cracks down the ECDSA they will obviously do away with it.
For re-distribution, there would be a quite easy and uncontroversial method: adding the coins to the future mining rewards to make the halving curve a bit smoother. IMO if this is an option the rewards should be moved into the far future, for example when the regular reward has fallen below 0.1 BTC or so.
This looks like a hard fork suggestion. Where the mining reward rules will have to be changed which will affect the initial standard halving schedule. This might lead to centralisation as large mining will stand a chance to benefit more.