I'd never buy a timeshare in Hawaii. The state law has changed over time in ways that do not favor owners IMO, and I don't want to deal with Hawaii probate. (well, I'll be dead, but you know what I mean.)
Hawaii is broke, and
DVC has a bad track record with waterfront dues. That combination is not exciting to me. Tax changes in Hawaii become your dues.
If you want to go to DL, get a a VGC contract and use it! It's expensive as hell, but still cheaper than booking Grand Californian cash, and the only way to get into the DVC rooms. Trying to book VGC without VGC points is setting yourself up to fail.
I think the DL tower and points are going to make RIV look like amateur hour. I'd be buying VGC resale now. Maybe your crystal ball is different than mine.
If your goal is to travel to Hawaii, you don't need Disney at all. There are better/cheaper/newer properties out there that are actually focused on Hawaii.