[rollcat]

> In that case can we start computing cryptographic products with quantum computers such that there is no gap?

QC solves one kind of problems, that are hard for classical computers, but not another (see all the links to post-quantum crypto in the comments). OTOH there will be a very large window during which QC will be cheap enough to rent by the hour on AWS, but equipping every lightbulb with a QC will be prohibitively expensive (think current GPU prices).