Blu-Ray does seem like it would be the storage medium of choice due to sheer capacity. Yeah, the quality won't be any better, but you can store a lot on a single disc.
But as has been pointed out, recordable Blu-Ray technology is still rather expensive. It might almost be worth it to just wait a couple/few more years for when prices come down to transfer everything over.
If you are worried about your VHS tapes deteriorating more in the mean time, depending on what you already have available in terms of HD space and how much VHS content you have to transfer, you could digitally transfer them now and just keep them on a Hard Drive until prices go down. Or, you could just store the raw data files on a bunch of cheap DVD-Rs for now (by doing this, you would be maximizing the DVD space for basic data storage, without the menus and layouts to play on a normal DVD player), and then eventually take those files and transfer them to Blu-Rays discs that actually play in BD players.