According to a new post from Ubisoft Support, you'll be able to take all three games with you from one console to the next, assuming you stay in the same console family - that goes double for your game progress, which will all be retained by the new Ubisoft Connect gaming and social hub. If you buy a digital version of the games on current-gen systems, you'll be able to play their upgraded versions at no extra cost when they launch.
The same goes for physical versions of games, but you will need to keep the disc and insert it when you play. If you're planning to get a PS5 Digital Edition or Xbox Series S you won't be able to upgrade that copy of the game, since neither console includes a disc drive. Ubisoft has more detailed breakdowns of the process for games on Xbox and games on PlayStation - the latter page also covers the upgrade process for Riders Republic, Immortals Fenyx Rising, and Rainbow Six Siege.
While Microsoft has moved to make all upgradeable games available for free through Xbox Smart Delivery, Sony is leaving it to individual publishers to decide if and how they want to offer cross-gen upgrades.