Just a slight correction so people can perceive this differently: it'll always be a ccTLD used as a gTLD such as .me and .tv are. However, that still doesn't change the value of names as it's just a classification that they belong to.
And I'm with
@Biggie on this.
Companies will always see the .com as superior, and that will remain the same forever unless the sentiment changes.
A good example of this is the Bitcoin vs. another altcoin with superior capabilities war; BTC will always come out on top even though it may never achieve 2000 transactions per second without an exchange (defeating decentralization) or allow other such features. The sentiment that Bitcoin is the leader in the cryptocurrency world was only strengthened by institutional investors. That also goes for .com as well, except it has decades over crypto.
Staying on topic, a better example of this would be the recent move of
TransferWise.com to Wise.com. There's no doubt in my mind that they could've still acquired Wise.io as the entire company's value that's currently using it could be less than an agreed-upon price to acquire it. Yet, the fintech giant still ponied up most likely 10 to 100x what they could've gotten the .io for to acquire the king.
Had Wise broken the cycle, it is possible that we could see a trend away from .com. Though I think that the trend would be outlived, as Wise alone doesn't have enough authority to change people's sentiment over .com.
Will .io still be a good investment? Most definitely.
The risk/reward is very favorable for .io investors in that they could get 10
solid .io domains to turn over for hefty profits whereas they would never near that for a solid .com. If an investor did go with a single .com, that would only allow them to focus on 1 domain with an initial investment until it's sold, which off-topic would relate to the #1 reason why real estate agents leave the industry in their first 6 months—they're unable to flip the 1 property they can for a paycheck of commission that would cover most new agent's salaries for a year so they view themselves as working for free and quit.
I suppose my advice on this is to go with .io as an investment strategy to ultimately build a great .com portfolio with profits. Alternatively, you can stick with the proven model of buying and selling .com too.