We need to fill 6 forward spots and 2 defense spots to reach a 23 man roster. In my opinion, there's no way you can send down McMichael, Phillips, and Haman Aktell. That brings it to 4 remaining spots up front and 1 on the back end.
Alexyev is NHL-ready at this point despite having a quiet pre-season, and is my pick for that last spot. Johansen and Iorio are better served spending a season in the AHL; Johansen because he doesn't look ready for the NHL speed and may never get there, and Iorio because he's still young and can benefit from a year cleaning up his game in Hershey before moving up full-time in 24-25.
The tough decisions come on the front end. To fill the 4 remaining spots up front, you have to go by who has looked the best so far. Snively hasn't done much to stand out. Mantha has had looks, but cannot finish. Aube-Kubel has provided a solid 200-foot game and is a great energy player for the bottom line. Protas looked shaky, but based on what we've seen from him at both the NHL and AHL level, it's safe to assume he'll put it together. Miro looks great, but he might take a year in Hershey anyway despite his stand-out performance in his pre-season appearance. Malenstyn hasn't been impressive, but also hasn't been bad.
Given all of these observations, I think the remaining 4 spots go to Aube-Kubel, Protas, Malenstyn, and Mantha. However, the MOMENT Pacioretty is ready for games, Mantha needs to go. Mantha also is likely not going to be playing every night if he can't get his scoring going. It's a results-based league. This team wants to compete for the cup again before Ovi and Backstrom are retired. Speaking of which, Backstrom and Kuznetsov look like their old selves again. It's very possible that Backstrom could be a solid 1C after having the full off-season to heal and train. He's at 100% and it shows in his game. That on top of the fact that his decision making and passing have always been his strongest attributes, it's very possible that he could make a meaningful contribution to the top 6 and the power play, which also allows a guy like Strome to fit in on the third line and provide serious offensive prowess there.
Line 1: If Oshie and Backstrom are at 100%, this could be a sneaky good first line despite their ages.
Line 2: McMichael has shown some serious scoring threat next to Kuznetsov and Wilson, who are great at making space in their own ways. McMichael and Wilson's defensive games help make up for Kuznetsov's defensive struggles.
Line 3: Milano and Strome have shown serious chemistry, and Phillips has an absolute howitzer of a shot. I think this line would do serious damage at even strength. All three are fantastic skaters, too.
Line 4: Protas and Dowd have serious chemistry, and Aube-Kubel brings a serious amount of energy to that line. I think this is a fantastic 4th line.
Pair 1: Sandin has shown some growth in his defensive game so far. I was hesitant about the idea of Carlson and Sandin being thrown together, but it might actually work.
Pair 2: Two smooth skaters who are good on both sides of the puck.
Pair 3: An incredible shut-down pair with some serious physicality from Haman Aktell especially.
I know everyone (including myself at points) counts the caps out of being a serious threat, but they may surprise and at least compete for a wildcard spot or 3rd in the Metro. Health, consistent goaltending, and responsible defensive play will be the keys to this season for the caps.