if we can strike at any sector from orbit... it would be good to have hard to capture strongholds ( really really hard nuts to crack).

after all you can retake it with a coordinated drop pod assault or the equivalent of it.

It is a single planet, and a continent at a time for now

if there are going to be main strongholds for factions then they will be captureable/destructible. How else are you suppose to completely eliminate a factions presence from the planet? Of course this shouldn't be possible till every single lesser stronghold/position of theirs has been overtaken. i don't think that'll mean that they are completely out of the campaign as that would really suck for its players, and what happens if it were to happen to Orks? no more F2P player? haha. no.

they'd get driven back into space on their ships and have a significant resource reduction or something.

That's one thing I don't get, 4 factions, lets all drop on the same continent. Surely one is sneaky enough to drop on the opposite side of the world to maximise early resource takings.

Or 4 continents at start taken each taken over by one faction then we fight over fifth one?

I like this

I would prefer there be a super stronghold to capture that will push people off the planet, with the ability to still deep strike from orbit/where ever they start.

Regardless of who ever has the bigger population, this is still a 4 way. Even if Orkz dominated in numbers, they would still be split between the 3 other player factions and the tyranids. Not only that, but that's why there's going to be an alliance system in place to make sure one faction doesn't steam roll the planet.

It allows the game to be more populated and concentrated battles, less wasteland with nobody playing

you don't all drop on the same continent. you drop on the same planet which consists of a number of continents. factions will most likely be located on separate continents.

at least, that seems the most logical thing to do to me..

Idea of the main well defended stronghold sounds good, but... I think it should be possible to capture it. For extra... what ever, requisition? Anyway marines will still coming via pods\deep strikes and can retake it. Eldar could use their webway gates, and orks.. i don't know.. growing up around like mushrooms?

But why fight over one continent?

Example : Orks, CSM and SM fight over continent A , Eldar think "fuck this , why waste our manpower/resources we go for the ( almost ) empty CSM base on continent beta."

Or it seems like it will just be Command and Conquer in my eyes. No freedom to go for that early deepstrike win, no mass zerg on an enemy fortress by the Orks.

We will just hold our bases and see who can take over this one random continent.

"oh Orks win there, we go for random continent 6 "

Each factions base " continent" not just main base needs to be attackable then