I dont think its either practical nor feasible nor even desirable to use Bitcoin in the day to day dabble of pizzas, phone credits, hairspray and sneakers. People try to, because of the misguided belief that Bitcoin value is somehow related to or deriving from its crossection in the retail market.
2) A single developer (Gavin) being able to screw up a software update and causing a fork that destroys a 10+ billion dollar business is not an option. See #1. People will want to minimize their possible risks to 10-20% loss for attacks or things like this happening.
3) Demand for anonymous transactions vs open transactions.
4) Practical hardware/space limitations of a single chain that has already been discussed.
5) The usage of PoS as a virtual bank.
6) How easy it is for a government to co-opt, attack, or take over a single chain. It's much harder to take over or destroy 10 at once. My estimate is, there will be 5-10 large coins.
7) Dozens more that I don't feel like typing.
Gavin hasn't been Bitcoin's best friend in quite some time and even nao the development accomplishments haven't been much.