HTC practically ceased to exist as a consumer facing company in the West due to this. I don't know of any hardware they've produced recently outside of their partnership with Valve on VR, and they're not the face of that relationship.
I feel like you’re exaggerating the impact of this single case on HTC’s long term viability .
The article says they rectified the issue in software right away. HTC died off in the US for many other reasons, I severely doubt this was one of them given it could be software rectified.
What killed of HTC’s mobile division was the inability to compete in the market against Google, Samsung and Motorola. I’m sure this case hurt some but given how quickly it was fixed, the import ban was likely very short lived. Especially because they had new phones available almost immediately after.
That article says they spun a new firmware almost immediately. I hadn’t heard of that case (Apple patents using computers to process structured data), but I thought some other thing did a much better job of screwing HTC over.
My first (and last) smartphone was a HTC Desire, and I wished HTC died before the day I would shell out over 500€ for that piece of smoking crap. It needed the mainboard to be swapped not one but two times under warranty before it could be used for more than 1 minute without rebooting (apparently a well known overheating problem) then, months after warranty expired, it suddenly died beyond any recover to became my most expensive paperweight.
I know I'm just an unfortunate drop in the sea, still I don't miss their products at all.