I don't think FF14 has had any significant discounts on black friday. Most of its deep sales happen randomly throughout the year though it is a fanfest year so it very likely could end up with a new bundled pack going up to include Shadowbringers since the expansion will be announced around the same time.
Shadowbringers might as well just be its own FF game considering just how well done the story was thanks to it being written by Natsuko Ishikawa (She wrote the Dark Knight quest lines in Heavensward). To be honest it was the best FF I've played since 12. As a bonus since you're waiting you have the benefit of joining the game after a major patch coming up this summer that is going to streamline the 2.0/ARR quest lines to prune a lot of the useless back and forth and pointless quests that do nothing for the story since it was a major slog to get through for most new players. Not only that but flying is being introduced for the ARR zones too so there's a lot of QoL that will make it more bearable.
