Even without quantum computing threat, I do not like to hold my coins on a single wallet. I have at least 3 different bitcoin wallets because I think it is better than having just only one. I still have two other wallets that I am using frequently. I think El Salvador are thinking like this also and which is very good. It is better not to leave all your coins in a single wallet, it is a not good.

For quantum computing, just do not reuse addresses and youbare safe.