MechaTarrasque
Hero
Since I don't expect anything to change in 5e (except there will probably be a lot fewer bonus action spells in the future), it occurs to me that 6e could simplify the action economy in a couple of ways:
1) If PF2's 3 actions take off, that could be a good way to go (and I could see concentration changing from "you can only concentrate on one thing" to "it takes 1-2 actions to maintain concentration (depending on the effect [and I am hoping there will be some martial concentration things in 6e])" with "controlling you summoned critter takes 1 action").
2) You could make it 1 PC-triggered action (PT Action), 1 move, and 1 externally-triggered action (ET Action) that could cover OA's and things like moving the target for hex/hunter's mark. That way you only have to worry about moving and taking a PT Action unless you kill something, the DM throws you a bone, or someone in your party has a PC with a class feature that lets him/her trigger ET Actions in his/her allies.
1) If PF2's 3 actions take off, that could be a good way to go (and I could see concentration changing from "you can only concentrate on one thing" to "it takes 1-2 actions to maintain concentration (depending on the effect [and I am hoping there will be some martial concentration things in 6e])" with "controlling you summoned critter takes 1 action").
2) You could make it 1 PC-triggered action (PT Action), 1 move, and 1 externally-triggered action (ET Action) that could cover OA's and things like moving the target for hex/hunter's mark. That way you only have to worry about moving and taking a PT Action unless you kill something, the DM throws you a bone, or someone in your party has a PC with a class feature that lets him/her trigger ET Actions in his/her allies.