Per 36 minutes, their numbers looked like this:

Out of curiosity, I compared their combined numbers to what Sato and Beal have done since Wall left the lineup just after Christmas. These are also per-36 numbers over the next 31 games:


The Sato/Beal combo is BETTER!
The Wall+Beal combo scores 7.1 more points per 36, but they do so at a marginal TS% of just .476. If that's what it takes to get those extra points, it's not helping. Furthermore, the Sato+Beal combo win the battle of possessions big time by getting 3.5 more rebounds and turning the ball over one less time.
Defensively, it's close, with the Sato+Beal combo probably having a small edge. John played pretty good D that year, but he was always up and down, with great defensive plays intermixed with laziness fighting around screens. I don't think he was any better than current Sato, who gives better sustained effort on every possession, but is often overmatched when he switches onto bigs. And current Beal is probably a bit better defensively than 2016 Beal.
Obviously, the primary reason the Sato+Beal combo is better is because Beal has taken it to a new level over the 2nd half of this season. It might well be the case that if you take current Beal and combine him with a healthy Wall, they would be better than Sato+Beal. But maybe not. Would Beal ever have reached this new plateau if he was alongside Wall? I seriously doubt it. Could he sustain if Wall came back and joined him? I don't know. Wall uses up a lot of possessions inefficiently. And he's not an off the ball threat when Beal has the ball.
Conclusion: Lock Sato up long term and try and trade Wall as soon as feasible.