[zoezoezoezoe]

Assuming I don't know or like this tech stack, on top of the fact that it doesn't open up any potential employment opportunities, I probably would start looking for a different job with a stack that I am familiar with and/or enjoy working with. If my company changed the stack, and if I didn't know if I like the new stack or not, I would probably stick around at least for a little bit, changing the technology you work with isn't always a bad idea, and can give you a wider range of experience.