Ian, you know I don't mean that in a... er... mean way, but that is the usual kind of reply I was hinting to. It's not that the effectiveness of sampling should be to be replaced by something similarly effective, it is just totally OP compared to everything else. Saying if combat would be as effective as sampling we would have the same issue is a whataboutism. It isn't, and if sampling wasn't OP, sampling away the invasions wouldn't be as easy.
Since the introduction of sampling, Frontier have reduced the system targets multiple times, as well as taking other pro-human moves like reducing the Thargoid ability to Alert uninhabited systems or strongly discouraging persisting in a system that reaches 100%. We have to assume they've done this to achieve some sort of desired overall war balance.
If sampling wasn't OP, then to achieve the same overall war balance they'd have needed to make everything else even more powerful, or reduce the system targets even further.
Yes, it's a "what if" counterfactual, but all the evidence points to:
Q: "What if sampling wasn't overpowered?"
A: "Then Frontier would have found some other way to ensure an overwhelming human victory."
And that would have been an improvement on the current situation - at least people would be doing more interesting things in Controls and uninhabited systems - but there still wouldn't be invasions because those pretty much require a net position where humans are losing systems overall.
Also, the point of people doing hauling and EVAC in alerts... I don't know how it is this week; but look at the past: Usually, the alerts are cleared by the sampling gang before the haulers and EVACers even start. Often, there is little more than one alert system left by friday evening. If you don't get to it right away on thursday, you pretty much missed it.
The last five weeks have had all Alerts cleared - but generally only by Wednesday night and the inhabited ones holding out longer than the uninhabited ones on average. This week is going a bit faster - partly because it started with fewer inhabited Alerts than average, and partly because of the new "activities disappear at 100% rule" being applied to Alerts too, and possibly partly because Frontier have
yet again decided that "clearing all the Alerts by Wednesday night? Too SLOW!" and knocked the difficulty down slightly (unconfirmed).
Are you thinking of the last weeks of Invasions where there were, say, four of them and they all got jumped on by every AX combat pilot in the bubble and wiped out in a day or two?
I have little faith in the line being pushed back so far that invasions reappear. We're going into the third, fourth month now without invasions? And it will take "months" for them to reappear? Come on.
At this stage it's up to the players if invasions reappear, since Frontier appears not to want to pull any of the very easy levers it has to do that. [1, 2]
The "natural" outcome is that the easiest targets get recaptured first, and because even sample-recovering an inhabited system close to the maelstrom is a tedious process, the most likely result from that is that it ends up with a stalemate line around 20 LY at each Maelstrom, which can be held by humanity easily, but which there's no particular incentive to push past.
So getting Invasions back will require
deliberately overstretching human forces by taking back a lot of systems within 15 LY. The only practical way to do that is sampling, and even then it takes a couple of weeks per system and everyone wants a break afterwards. And it'd need a bunch of them running simultaneously to guarantee that they weren't shut down at the Alert stage. Hence, months. Minimum. Unless Frontier sees that it's taking too long to crush the Thargoids utterly and reduces the targets again, of course.
[1] One more interesting option than just increasing the targets or adding another eight Titans would be to make inhabited systems within 20 LY skip Alert and go straight to Invasion.
[2] To repeat: at this stage, they could set the effectiveness of sampling to zero and it would still be months before Invasions returned, too, if there were no other changes.