No one takes .so seriously even after notion.so. Hell, I'm sure countless people still try .com before giving up and Googling "notion" (or maybe that's just me, but I doubt it).
That's how people learn. The world can't stay on the dot com paradigm forever. The new startups coming out called something ridiculous like "wuua" just to snag a dot com should be a sign to everyone that it's time to move on to other TLDs.