Well, not completely, per se. But the latest chatter about both Kyrie Irving and Kawhi Leonard has me wondering.
Those of us who were fans in the 1990s might remember how the Bulls utilized Ron Harper in their backcourt with Michael Jordan. Harper was no longer an explosive athlete by the time he came to Chicago, but at that point he was a savvy veteran who fit the team's identity. What he was definitely not was a point guard. Given the team's triangle offense, it didn't matter. All you needed was someone to bring the ball up the court, and the players all ran the offensive system from that point forward. You happened to also have an all-world defender in Jordan who could clamp down on speedy PGs on defense, if you needed it.
The point is that the league has seen a no-PG starting lineup before. Multiple times before, in fact. I remember a few years before that, Steve Smith and Brian Shaw started for the Heat and called themselves "one-and-a-half" guards. You don't need a little speedy guy in the lineup.
Could the Celtics trade Kyrie for Kawhi straight up with this in mind? I'm doubtful for other reasons -- there is still a health concern about Leonard, and no guarantee that he'd re-sign past 2018-19 either -- but it's possible that it could work from a pure basketball point of view. You'd have very solid ballhandlers everywhere (except maybe Jaylen Brown), meaning there's multiple guys who can bring the ball up the court. Everyone in that lineup could shoot, pass, and make plays. They would physically beat the pulp out of smaller backcourts. (Pray for Lillard and McCollum.)
On defense, you'd have an issue chasing around the speedier PGs. But you've got Jaylen Brown, who's young and fast enough to at least hang with players like that. Meanwhile, you could switch pretty much everything and never be caught in a defensive mismatch, which as we've seen is a huge asset in the playoffs.
Again, I think the Celtics really like Kyrie Irving as a player and a teammate, and I think Kyrie likes them back. There is a really strong chance he re-signs and at this point I see no reason to part ways with him. But if the Celtics worry that he might be gone after this season, I wonder if they'll just scrap the whole PG concept altogether.