I think it's worth playing in spite of its flaws, and maybe you'll have the chance to check it out for yourself next year.
As mentioned above, you shouldn't worry about losing the games once the holiday offer is over. If not, there's time galore to announce it in January.
You can download Black Flag starting December 12 at 6 a.m. PST up until December 18 at 2 a.m. PST.
World in Conflict turns 10 this year, as well as the entire Assassin's Creed franchise. So a re-release would do good for the series, giving it the exposure it needs.
Ubisoft hasn't confirmed the HD remaster for the title that released in 2014 for PS3, Xbox 360, but it would seem that fans will indeed be able to enjoy the Assassin's Creed IV Black Flag sequel for current-gen consoles. As with any such rumor, treat it with a grain of salt until we receive official word from Ubisoft.
You can check out Assassin's Creed Rogue now for Xbox One (backward compatibility), Xbox 360, PlayStation 3 and PC.