Basically my understanding of it is that some things (i think maybe leaders iirc) can carry over but for the most part it is indeed a wipe. The gist of it is mainly to align it more with the physical card game (Shadowverse Evolve) which notably i think has less classes, some leader-specific mechanics and stuff.
They were also going to add in a bunch of other things in the new hub world for this one (such as fishing, dungeon crawling and mahjong minigames, which i guess would've made it feel more like an MMO of sorts in a way) but now it seems it's more of a standard social hub area, which i guess is still a notable difference.
Overall, they've been teasing it for a long time, to the point that it was supposed to release around a year ago, and shadowverse 1 has basically just been in life support mode ever since (they wrapped up the story (which is like, over a hundred hours of cutscenes split over 20 arcs lmao), stopped doing new expansions and everything), so they kinda need to do it now, but I do agree that it is going to be a tough sell. At the very least, the physical card game they're basing this one off is pretty much universally regarded as better than the digital games as things stand, so i think it's pretty well poised to be viewed as an upgrade at least.
Also the other edge it has going for it compared to the original is that they have improved card acquisition considerably by (finally) adding a free card pack per day (compared to about one every several days) and having guaranteed legendaries for 10 packs, which was only a thing available sometimes for paid 10 pack draws in the original. there is a bit of a down side that they are making disposing of extra cards less efficient in this one by preventing you from get rid of duplicates unless you have more than 3 copies. i'm hoping that they at least let you get rid of say, non-animated cards if you also have animated ones, since in the original game they treat them separately, but because of that i'm not very hopeful