That said, I would predict the following:
- As the company grows, they have trouble hiring specialists or more senior people, since they're competing with other companies for those people, but without the flexibility to offer a comparable salary. They could solve this by paying their highest-paid person what they're worth, and everyone else the same, but that could be prohibitively expensive.
- The need will develop for people who, though valuable, are plentiful (eg, a janitor, but fill in any role here that's generally near the bottom of the pay scale). The decision will be "We'd really like a janitor, but not enough to pay $X", where X is their everyone-salary (which has to be high enough to attract their most valuable people). As such, they'll be hard-pressed to hire roles that aren't really worth that much to them.
Of course, you can solve either of those by having more money than you know what to do with. So, if they're wildly profitable, it's a system that'll keep working.
That's just my prediction, though. I'd love to see a followup blog post in a few years describing how it went.