I'm sure we'll see an alternative sprout up pretty quickly - in the intervening 10+ years since the DistoX was first developed the world of amateur electronics has become much more accessible. You can now easily get your hands on knock-off laser distance meters (LDMs), Bluetooth LE prototyping boards, accelerometer and magnetometer breakout boards etc, each for less than £25. And PCB printing is now much cheaper and more accessible than it once was.
I've been fiddling with microcontrollers for a while, and a couple of months ago I decided I'd try and make a DIY DistoX clone using cheap parts. It's never going to come close to the accuracy, robustness, or usefulness of the real thing but I am enjoying making it, and learning loads in the process. I'm not far off having something that I can take underground to test out (using the DistoX communications protocol for compatibility with existing apps). I'm quite sure that a concerted effort from a group/individual that doesn't have to learn everything as they go along can get a working replacement up pretty quickly.