I can't say anything about future development, but the addition of RealTracks from 2009 on is really a huge improvement over the MIDI only previous versions.

I was in the same boat. I used version 4 or 5 until I couldn't run it any more in classic mode on my new Mac.
Then I went to version 12, and it was somewhat of an improvement from earlier versions.
But ver. 2009 (and now 2010) is a big step forward.

You can still use SampleTank via the IAC bus, but I've found that since I've started using the RealTracks I'm using a LOT fewer MIDI tracks. If I need to record MIDI I usually do it in another program, after I export the RealTracks arrangement out of BiaB.

The only downside is the RealTracks take up a lot of room, 93 gigs for the full BiaB installation on my machine.
Of course you don't have to load all the RealTracks on your hard drive, but what's the fun in that ?

The addition of RealTracks alone is worth the price for the upgrade from Ver. 12, IMHO.

Of course all this this is just my opinion, YMMV.
Hopefully this helps.

- Jay

MacPro 5,1/12 core@3.46GHz -- OS X 10.15.7 -- ATI 7970 -- 32 Gig RAM -- Crucial 500GB OS SSD -- Samsung EVO 1TB Audio/Sample SSD -- BIAB 2024 -- Logic Pro X -- Cubase Elements 14 -- Too many plugins