Honestly the best rework imo is keep the current summon style but rather instead of the two buttons that we have now, revert it to Egi Assualt 1/2 and each on does a predetermined attack set, much like how automaton and Esteem works, but you are the one to give the command. It would keep the summon fighting alongside you and SMN could then revolve around either buffing their summon or attacking alongside them. It's also not a limitation of the code since bahamut and phoenix literally do the same thing, stay on the field the entire time and you command them when to do their big attacks.

However I'm willing to see where they take this since this is just the foundation of what's to come, despite being very bare bones at the start.