This might already happen implicitly. The forks so far showed that there is a large market for a cryptocurrency that stays mostly as it is. None of them comes even close to the market value of the cryptocurrency on the original chain.
That's not true at all. In fact the pioneer, bitcoin is changing every couple of years. We have added new things to the protocol such as new OP codes, have changed some consensus rules, fixed or improved some issues, added new script semantics, and a lot more.
The reason why "fork coins" (better said copycats) have been dumping ever since they were created is because they don't have anything new to offer, they simply copy everything from bitcoin and basically only change the name to "bitcoin-something".
Due to its mere size (measured by market cap), there is quite some incentive for Bitcoin to stay conservative with respect to changes in order to keep everyone in the boat. This is not the case for small blockchain with a smaller user base that might just accept whatever protocol changes the developers push into the code.