Even 5 models per company would be bad for the survival of that company.
- You need a big button dumb phone for seniors.
- A basic smart phone for kids
- Dumb phone for people who don't want smart phones. Or those prohibited by law from having a smart phone.
- Basic smart for low income.
- Premium smart for most
That's five. No corporate friendly model, no alternative form factors for people that want to burn money (the most profitable phone), no mid range. Just extremes. Now if a competitor comes out with a new idea you have nothing to retain customers. Now you're right for a hostile takeover over.