Lots of things, even more if convicted which did not happen last time. Establishing a precedence that you shouldn’t incite a riot is there. Hopefully will help splinter the party where radical right members have somehow taken the wheel from the classic conservatives. Makes party members on either side take a stand and it gets documented, which is mostly talking points for political theater but if Trump is discovered to have had deeper relations with political enemies or other undesirable actions revealed, politicians who backed Trump will carry some of that stain by association, which could hurt their re-election/party.

If convicted: Prevents him from running again in 2024. Removes 1 million dollar annual travel budget and taxpayer-funded secret service protection which is notable if you think he’s broke/in massive debt like many people do.