Quote from: vapourminer on Today at 11:23:43 AM

yeah and i figure normal day to day TXs on top of that.. so all those need to be squeezed in too.

but can wallets and such be made so that, say, a TX from a quantum vulnerable addy to any other addy, quantum safe or not gets change back in a quantum safe addy? at least some day to day TXs would get rolled in for free that way, kinda.

edit: wording, as i suck at it

What you refer to here specifically is not possible. Unless specified explicitly "change" goes to an address that you own. If you are sending from a quantum vulnerable address the change will go to another address in the same wallet which would again be vulnerable. There is an approach how this could be done but it is way too different to how Bitcoin works right now. The protocol could make it mandatory that coins only go to quantum safe addresses and never to any old address format. However, this would break all wallets currently in existence.

I think what we are more likely to see is a more gradual rollout as with SegWit and bech32. Some wallets were supporting both formats and some had the option to force the change to go to the same address format. That is, if you were using bech32 addresses the change would go to these addresses. The adoption of these addresses was a bit too slow for my taste, but I expect the adoption of quantum resistant addresses to happen much faster.

I don't think we will have a big problem with transitioning active users or entities especially those with large financial stakes. It is not that people would not want to do this or that many are not slowly getting aware of the slowly incoming quantum threat. It is more that as of today there is nothing that you can do about it. No proper solutions are even close to being implemented. I believe that once a solution is deployed, that there will be a prolonged period of an intense fee-market as people will compete to switch to these addresses even if the threat is not yet active.