I am speculating on something I am still trying to get my head around, but it seems to me if there is a danger cloud for conventional domain investing it is the decentralized name system (e.g. Handshake). If as a company you can buy your precise name forever (or for the life of Handshake I guess), not subject to control by someone else, that will be hard to compete with, but only if it becomes easy and accepted to use decentralized extensions.
I think it is still possible Handshake will crumble without major impact, as some previous efforts did, but if it takes off, it is something we should all worry about.
I think for a long time there will be strong demand for excellent .com, and some country codes, and great matches across dot in new extensions, some legacy and some other TLDs.
I don't think any one new gTLD will become a serious competitor to .com. That said, I think many new extension domains will be actively used in 10 years.
Bob