This is just beyond hilarious. Why the fuck would you even think a centralized payment network supported "by a Fortune 500 company or billionaire with a slick multi-million dollar marketing campaign" would bother creating a cryptocurrency. Do you understand the necessity for the blockchain and POW design and why it is totally worthless and ridiculously inefficient under centralized control?
Centralized control works for linux. It's better than the decision-making gridlock of the core devs.
To answer your question, we already have centralized control of code development, but an alt could have better management of code development. Maybe they just want a crypto that scales better and starting over from scratch is easier than convincing people like you to improve Bitcoin. They could pay for the marketing by selling pre-mined coins and kickstart mining with a guaranteed price floor.
The maximum it would take to absolutely guarantee a 100MM market cap would be $100,000,000 but would almost certainly be a fraction of that. Throw in a plunge protection team to smooth out the most extreme volatility and you'd have a coin anyone and everyone would want to buy or mine.