I don't really see the potential in these games period. It's certainly not going to measure up to BW2. There just... isn't a whole lot to build on with Alola, the region's pretty full up aside from a couple of side areas that they could expand on, so we won't really get that huge, BW2-esque expansion unless they add new islands (which I seriously doubt they will). The regional dex is already pretty large and varied, so a dex expansion won't really do much. That pretty much just leaves the usual extra storyline elements and new features, so it's probably going to be more in line with a traditional third version than BW2.
And while BW2 was the only one of its kind and this would be about average for the series, the thing is that BW2 has really opened the fanbase's eyes and raised the bar in terms of what updated versions can really do. Look at some of the fan comments about what kind of games they want to see and you'll notice a lot more people asking for sequels now. When ORAS was first revealed and they gave that PR statement about it being a "fresh take" on RS in a "new world", everyone thought they would be sequels, only to be let down when it wasn't. Some people have been throwing around the idea of following Lillie to Kanto for BW2 style Kanto sequels or making Sinnoh sequels when it's inevitably Sinnoh's turn for remakes. And now with this game, pretty much everyone is hoping it'll be more like BW2 and less like a third version. So even though BW2 was only one sequel, people are starting to expect more of them and going back to regular third versions and remakes feels like a step back.
So yeah, it's still early and they could surprise us, but in general, I don't see any way to make a second visit through Alola exciting. At best it'll be a poor man's BW2, and I'm not even sure of that. The wording makes it sound like it could just be a generic third version.