It depends how its done. Having to drop what I'm doing to have to go all the way back to a location I've already conquered to keep it from being taken back sounds like padding to me. I'm glad that capturing a keep meant I kept it. The problem was the game barely had any keeps at all, so if MEN truly does have those outpost things then I hope they go all the way with it. I'd rather micromanaging be focused on me building my MC and my squad, not micromanaging dozens of colonies.
I'd love it for each outpost take over to have proper build up. How about before the take over you have a multi-tiered quest chain as you go around the planet preparing for the outpost take over. Have each outpost have a general of some sort, each with a unique personality. Have them send out troops to try and stop you as you explore the planet. Give us some cutscenes of our hard work paying off. Have the outpost take overs be more than just kill everyone in sight. Make them feel like major power struggles between two opposing forces.
Maybe I'm asking too much.
I think they might split the middle and say that for each area that you've conquered, you have to play MP to keep it safe. Kind'a like what they did in ME3 and DAI. But only more proactive, I guess.
EDIT : As a matter of fact, I'm pretty sure that this is what they'll do. Ya know those event that they have each week? Well, those are the BioWare guys (and girls) trying to tell us that they are really interested in our games. So, they'll write an algorithm for whatever system has to be taken over and then for whatever system is most taken over, what system is taken over first, last, etc.
And then write an aggro dump for that algorithm.
EDIT x 2 : Sorry, I just started playing WoW again recently. (I know, I know... I agree it sucks) Sorry for the WoW terminology.