Rival ebike maker Cowboy is making an app[0] that supports some VanMoof bikes and they say it will support more models in future. Meanwhile, you can download your bike's encryption key and passcode from this other website[1].

It appears likely that as long as you have this info, third-party apps like Cowboy's or others will be able to work. But getting the info relies on VanMoof's servers being up, so if you have a VanMoof bike I recommend downloading yours ASAP just in case.

FWIW, I have been using a VanMoof Electrified X2 in Tokyo for about 4 years. Great bike, but glitchy software. The bike plays sound effects like "unlock" at random inappropriate time, and the app on the phone frequently displays useless/incomprehensible alerts.

But one of the good things about VanMoof is that they have an API that already somewhat supported third party apps, like this one[3].

So I think as long as you save your bike's encryption key and passcode, you're good. I don't think your bike will be bricked after that. (But it could be otherwise, because those details are needed for a non-VanMoof app to control the bike, and if VanMoof disappears AFAIK there is no way to get them after that.)

[0]: https://bikey-app.cowboy.bike

[1]: https://keyexporter.grossartig.io

[2] https://moofer.app