It doesn't have that big of a future. If a developer wants fame or recognition, they will start their own coin rather than stay in BTC's shadow. If a developer wants profit, they will start a coin, buy while it's low or have some kind of IPO or something, then build features to increase their worth. It's not really something that interests traders as much either compared to the altcoin penny stock lotto.
It is very possible that spin-offs
don't have a big future. This would suggest to me that the economic majority prefers bitcoin exactly as it is.
I disagree that developers who want fame and recognition are best to work on alt-coins. The biggest developer names in crypto are individuals who work on bitcoin--and these developers who have already made a name for themselves will be in demand as long as crypto is in existence. If you want to establish a name for yourself--perhaps hoping to get scooped up by BitPay or start a consulting business--you are probably better to innovate for bitcoin than you are for altcoins because there is a vastly larger user base that will be interested in and talking about your work!