Make no mistake about it, the closest competitor fro ETH is NEO. Other potentials are EOS and ICON. But if I had to say could ETH be overtaken within a couple of years by anyone, then I would say NEO, for all the reasons already mentioned in this thread.
I agree with you NEO I think is the best competitor for Ethereum, I see the NEO development is quite good and increasingly popular, many people call NEO is EThereum from China so I am now very confident that NEO will be Ethereum's toughest competitor in the future.