I wouldn’t count on big companies ever going that route, to be honest. The decision-making people there will likely never trust Lemmy or similar software enough because it’s not like them - not proprietary, not closed source, so they’ll keep wasting money on making their own shitty websites with their own shitty forums if they ever want to give their communities an official place to hang out.
I think it’s more of an ego thing. The people with healthy egos probably never end up as execs in companies as big as Reddit, and the people that do are likely driven by something else other than the desire to actually build a platform that respects its users and works well in cooperation with them - “I’m smart, I’m sexy, I know better than these plebs making us money”.