I think, he is likely to bring back the public charge rules they had before. When I filed the AOS for my spouse there was a lot more paperwork but it was manageable, the rule was as ended before my husband has the interview so we wasted a lot of time and money on the extra documents.
Fees could go up but that is normal so I doubt they would raise them exorbitantly or anything. The cost of processing cases have probably increased so new fees will probably be needed.
The more unlikely changes, would be to limit the categories of people eligible for a visa. They has been some push to remove sibling and parent green card options. I doubt they would go for the change but it’s not impossible. Of course this is all theoretical now, won’t know for a while what the actual plan is.