We have enterprise customers - you don't need artificial lock-in for that.
It's not all about TAM. There are many problems out there with massive TAMs that can't reasonably support a profitable functioning venture.
Enterprise in the most traditional sense is a game about huge deals with eye-watering cheques being signed. It's very much alive. It's perfectly fine to target just the top 500. You could even potentially close just the top 5 and retire in comfort.
TFA's title, literally, is "Enterprise is Dead" -- it's anything but. The thinking in TFA isn't necessarily wrong but it is a sweeping generalization that I would even consider dangerous.
You can absolutely enjoy massive success running a traditional sales pipeline and catering to the world's largest and most successful businesses. I'd rather have 50 customers each paying me $1MM/y than a million customers paying me $50/y.
