I highly doubt we keep Barbashev on the 4th line at the start of the year when he is coming off the season he had, especially when that puts Brown and another in the top 9. Barby had 26 goals and 60 points. That's 5 times as many goals and 3 times as many points as Brown has in his NHL career.
We are no longer deep enough to roll 4 scoring lines. Acciari is a good 4th liner, but he puts up no offense. He's much better off anchoring a defensive 4th line. We'd be really neutering Barbashev's offense to put him with him and whatever other guy we wins that line. Given Barby was one of our best goal scorers last year and we lost goal scoring without adding any, I see no reason to put Barby with Acciari with less ice time.
If we have to go with pairs where one of our 8 best is with Acciari as the basis of our lines, I'd rather swap Saad and Barbashev, then have one of the youngsters win the top 9 RW. So we'd have an offensive line with Barby-Brown-Bolduc, and a defensive line of Sadd - Acciari - Highmore.
I don't really like that either as I'd rather have our 8 best in the top 9, with a spot for a youngster or new signing to earn.