Is Jaylen more or less likely to make All-NBA next season if its positionless?
I think the games played is a bigger deal than positionless. I think positionless will help (assuming next year's field mirrors this year's) with no worries about people leaving Jaylen off their ballot because they considered him a guard but ranked him 7th-8th there but had him above the 5th-6th ranked forwards or vice versa.
While some will argue guard is deeper, and so positionless will hurt Jaylen, I would use All-Star voting as a proxy for now, where Jaylen finished #2 in media voting for Eastern conference backcourt. Seems he has the voter's respect.
Games played is going to be the bigger help I think. If these new voting rules were implemented this year, it would mean LeBron, AD, Lillard, Durant, Kawhi, Curry, Halliburton, Morant, Irving, Booker, Harden, George, JJJ all won't be eligible, and I expect this pool of players to get a decent chunk of votes.
That leaves: Jokic, Embiid, Giannis, Tatum, Doncic, Butler, SGA, Sabonis, Randle, Markkanen, Fox, Edwards, Mitchell, Young, Garland, Brunson, Lavine, Siakim, Bam, Bridges, DeRozan, and a couple of others I'm probably overlooking. I like Jaylen's odds to be in the top 15 against this pool of ~20-25 players.
Of course, next year's pool will be different. Some people not in the conversation this year could be there next year (Ball, Zion, Ingram, Banchero, Wembanyama, Holmgren, etc.), others could be healthier (Curry, Lillard, Durant, Morant, Booker, etc.), but some current healthy people will get injured and/or decline while others might leapfrog Jaylen. Next year, Jaylen will probably be ranked somewhere in the 15-30 best players in the NBA (ESPN had him #22 before the start of this season); Jaylen healthy, C's winning, and a normal distribution of missed games among the top players in the league is what will help Jaylen the most I think.
Inadvertently, the new rules might help Jaylen make it this year. I'm sure there's voters on the fence if they should vote for guys like LeBron, George, Curry, Morant, Lillard, thinking to themselves, did this player play enough games? Now that the threshold has been established, it will be easier for them to justify that this player did not play enough games to get a vote. Will be interested to see if impacts voters. LeBron got 169 points last year playing 56 games, will end up somewhere between 51-55 this year. Let's see if his votes drop off significantly.