Your dreamer if you think some altcoin magically take over Bitcoin. Most devs working on Bitcoin software, and the software is so reliable only because of them. If not Bitcoin, no decentralized cryptocurrency will succeed
Well, in the same vein, in the 80s you could have argued that if one day everyone will have a computer in their pockets, it will be made by Commodore.
Where is Commodore today?
As for the flaws, there are three major ones (to rule them all and in the darkness bind them):
Deflationary model.
It's a horrible idea, and a defunct system purposely discarded in the early 20. century. The problem with today's fiat currencies isn't stable inflation, it's manual control by governments in form of easings and tightenings. A currency with a stable, fixed rate of inflation would be preferrable. Deflation favors the lender (stockpiler) as opposed to the borrower (innovator / producer). For example, you buy a farm. The value of the farm will drop with time due to deflation, while the borrowed capital debt will stay constant (and accrue interest). It was bad enough a hundred years ago, believe me you don't want it back.
Messed up mining rewards system
The mining infrastructure, due to the borked rewards system, is ultimately self-destructive, leading the network toward centralization and eventually evaporation.
I've already written about this extensively. It pretty much counteracts all the big pretty words that were said in the manifesto, like "independence" or "decentralization".
Disproportionate holdings of early adopters
Due to the mining curve, the majority of Bitcoin is held by a few early adopters, and this will not change. Unless the goal is to create a new evil financial elite / illuminati to replace the current one, I don't see what good Bitcoin can do for us.