Not at all. The validators get a small portion of the transaction fee for themselves and certainly they could ask for something different. But the ETH burn is built into the protocol. In theory that could be changed, if you got agreement not just from validators but from the rest of the ecosystem too. But nobody wants to change it. 1559 became very popular within days of hitting production, since it improved user experience so much. And the bigger the ecosystem gets, the harder it is to make fundamental changes.

But sure, in theory all the protocol rules could be changed. In theory Bitcoin could change their 21M supply limit. In theory, a company could sell its fixed assets and pivot to an entirely different business, or the US could change its constitution and take away property rights. But in practice, we usually estimate values based on the way things are working now, and put little weight on unlikely fundamental changes that might happen someday.