If Ethereum scales strongly and maybe even more than most investors expected, I think it is not impossible. Out of a sudden all applications would have the perfect platform to go to and that might drive the price up a lot. When full POS is rolled out with more scalability solutions and there is an ever-growing need for gas it is very attractive for investors to hold onto Ethereum.
in principle it is true what you said that investors will determine whether ethereum can also develop well as desired. maybe after a new system starts to come and the benefits that investors want, anything can happen and the ethereum platform gets stronger and many continue to take advantage of it.
but the problem is ethereum is catching up with time because now many other platforms are popping up due to their own effect. if this is ignored, it is likely to be constrained and difficult to imagine because there will be many platforms that can be used by adjusting the price to what is needed.