In a marketplace of alternatives, with marketing lower network fees, is Eth likely to be overtaken as the most important smart contracts platform?
Short answer: No.
Why is that likely the case? Because probabilistically, if 90% of all the blockchain developers are trained on EVM compatible languages, then when innovation happens, the first place it is expressed is likely in an EVM compatible language, most likely on Ethereum mainnet or testnet. Which means that while it's not impossible for innovate to strike on an alternative network, it's simply highly likely for the future to be Ethereum based.