Vader is Vader

Ok there are a few expectations when you purchase a new legendary, here's journey, or Galactic legend.

1. They will be meta for around 6 months or so. (Though we'd with two at a time this expectation would b we'd that they would be able to get first but not necessarily meta)
2. They will remain pretty competitive in arena for around 6 months after that.
3. They were will likely have continued use in other areas of the game and be decent for years to come.

That's pretty much what to expect. I don't see where that is any different were with Galactic Legends than with another new character type.

And Rey came out around December. Last I checked she was still at the top of most arena shards.

Even if the vader rework is part of a meta shift and it might be, people have had Rey to play with for 6 months. Ep got a rework and shifted the towards the sith but it wasn't really complete until sion and later trays became available.

Hopefully, the pattern is followed and the next meta is a new game mode reward. If that's the case, then Rey and Kylo will likely be important to have for it so people that bought them will likely get the next meta too.