sellpressure by merchants is a myth. I don't believe this story. Merchant use is very small compared to tradevolume.
I think the story is a try to explain this market but i think it's not the correct explanation. There is other more important factors than Microsoft selling 500$ worth of items every day for btc.
so in your view, everyone realized how useless this bitcoin tech is and quietly dumping everything they have, i mean that's the only way we could actually reach a Zero?! why now? why not earlier, why ever at all?!
no, not everyone realises how useless it is (because it's not). But everyone realises pumping against an inflationrate of 10% annually + Fatty selling your coins back to you + mad asians shortsellers is bogus and that's why it doesn't happen, breaking the longterm trend and trigger serious doubts and maybe even big panicsells from bagholders.
If it breaks below and doesn't rebound you'll see a selloff and spikes after that will be used to sell more off - that's when the bearmarket never ends and hope dies. Going to zero and actually stay there will take a year or two but it can be at double digits in the blink of an eye if this line breaks. I wouldn't be surprised.
Alternatives will be booming. Everyone will come out of the woodwork and propose their solution to why bitcoin failed of course.