Dylan Holloway projects to be a solid middle six, and potential top six, forward. His NCAA coach, and the Oiler scouting team may feel he is NHL ready, and it would be a great thing for the Oilers if he is. However, he has not yet played a professional game and it is possible he spends time in Bakersfield next season. It is difficult to imagine he will be able to push RNH out of the top six, its possible, but highly improbable.
Philip Broberg is another promising talent that will likely need some AHL experience before getting a full-time gig at the NHL level. No doubt he will start his NHL career on the bottom pair, its quite possible he gets that opportunity for a few games at the beginning of next season. I think he will probably play most of the season in Bakersfield though. His NHL opportunities should be heavily influenced by Evan Bouchard, Dmitri Samorukov, Markus Neimelainen, Kris Russell, and any other depth defender the Oilers bring to camp. Bouchard is unlikely to start the season in the top 4, but he could be in that position by January. If Larsson is still an Oiler, he will probably start the season playing with Duncan Keith, and Bouchard will start on the bottom pair. Tipett will not want to have two rookies comprising the 3rd pair, so Broberg may have to wait until Bouchard ascends the NHL depth chart. Samorukov and Neimelainen both have more pro experience than Broberg, and they also have AHL experience. Neither have the talent or potential of Broberg, but right now both should be in a better position to adapt to NHL competition. Unless Broberg completely dominates the AHL, I think either, or even both, of those other two prospects will get NHL time before him. Of course, the Oilers might bring back Kulikov, Koekkoek, or some other veteran and that would surely mean Broberg will not be an NHL regular next season.
Stuart Skinner had a solid AHL season in 2020/21, and he probably needs another one before he gets a shot as an NHL regular. Ilya Konovalov is expected to be strong competition for Skinner, and that dynamic will be very interesting to watch.
Ryan McLeod is most likely going to start the season centering the fourth line. He seemed to be a good fit in the bottom six during his 10 game introduction to the NHL. If he struggles he may get some time playing left wing, but I think he is expected to become Edmonton's third line centre of the future.
I see you have not included Tyler Benson in your roster. I wonder whether different circumstances might have given him an opportunity to audition at the NHL level last season. He definitely has most of the attributes required of a middle six forward, although his skating has been a bit of a concern for some. I am looking forward to a possible competition between him and Dylan Holloway, both should be strong considerations for the third line.
Looking at the RFA contracts you have proposed, I wonder if Ken Holland might hold a tighter line with respect to salary. Skinner will probably remain in the AHL and should be paid accordingly. Yamamoto struggled last season, and his draft pedigree and strong 1/2 season debut should not cloud the fact that right now his stats point in the direction of a third line forward. Many project his contract to be more than you have suggested, but I see no reason why he should not be bridged with a salary under $2,000,000. He won't be paid as low as Jesse Puljujarvi though. I think there is $700,00 to $800,000 in savings to be had from those two contracts.
I am not a fan of the trade with Buffalo. I appreciate the sentiment to move Zack Kassian's contract, but adding a top end prospect and an early draft pick seems excessive. In my opinion, you'd be better off clearing cap space by burying Turris and buying out Koskinen. When he has his A-game, Kassian is worth every penny the Oilers pay him. He is an emotional guy and I suspect the suspensions and injuries he's sustained these past two seasons have had a detrimental impact on him. If there are fans in the buildings next season, he may just overcome those issues and you might see the Zack Kassian that Oiler fans love. Holding onto him, and giving him that chance to rebound, also means you hold onto a near NHL-ready prospect and an early draft pick. If you are include to trade those assets, they should get a conversation going for a legitimate scoring third line centre.
Having provided the above, it should come as no surprise that I don't think it is necessary for the Oilers to sign Jordan Martinook. He'd be a nice add, but I think the combination of Benson and Holloway, in concert with the versatility and penalty killing acumen of Shore and Archibald may be sufficient, especially if the Oilers get themselves a scoring centre for the third line.