I loved the Ardennes Assault campaign. It had a persistent manpower pool that you had to be aware of lest you run out of men to build or reinforce units, some of the objectives were timed, there were bonus objectives, and there was some variation over the same levels so the same map could play differently in another playthrough.
From what I've seen in the DOW3 campaign so far, there doesn't seem to be a limit to your pool of soldiers which I guess I can live with and there was a form of time limit in the mission we saw where if you wasted too much time then the second portal gate would throw even more Eldar at you from the east, and there was a bonus objective to find Space Marine supplies around the map.
But before I continue, I have to say.... the level actually doesn't look hard For a late game mission, it looks rather easy. Yes, the orbital laser is one of the reasons but it seems like with proper unit micro-ing and composition the mission can be done rather quickly, like about 20 minutes (which a DOW3 Twitch player finished in 25 minutes whereas a lot took an hour). I think I can attribute that to playing thousands of hours of COH2 online but regardless, I do hope DOW3's campaign can be more challenging and has replayability.
I know the Time limit penalty is divisive in RTS games. Some people love it, some hate it. Personally, I love time limits like in Dead Rising and Star Craft 2 and wish more games had it. In a perfect world it would be a choice but given how time limits fundamentally change the game, it would be hard to implement both as an option. That's why for DOW3 I like that there seems to be a time limit that punishes slower players but I would also suggest a time limit that would reward players outside of the campaign. Assuming DOW3 has something like COH2's microtransactions, perhaps beating the time limit for bonus objectives or the entire mission would give you points to spend on in Multiplayer whether it be Elites or more customization. And it would make the campaign more difficult and tense too.
So basically, I think timed (bonus) objectives could make the campaign more replayable and difficult just like in the Wargame European Escalation campaign. And accomplishing these objectives within the time limit would reward players to use as ingame currency, so there'd be an incentive to do it (in WarGame, completing timed objectives gave you Command Points to unlock units)