If you're worried about going into new dungeons as a tank, you might want to look at getting a second class with a different role? It's so much better to go as a healer or DPS first and just "follow the leader". I'd hate to be learning dungeons as a tank, and the queue times aren't that bad.

Also if you're following the story, it's quite a jump from the start of Stormblood to where the skip would put you. It's my least-favourite main story but the post-credits story has been good and sets up a number of new reveals and information.