I actually think A BEST 3 is a release you can expect at one time or another as it has predecessors. In my opinion, it's probably more realistic than receiving another single...
If we were talking about something a bit dreamy like Ayu releasing unused tracks and the like, then yeah. But still, it is better to dream and be disappointed, than to never dream at all.
Back to the DVD though, I can't wait to see the cover.