The same thing will happen that happens every other time there's some outbreak "emergency": Nothing.
That's exactly the goal: ensure that as many people as possible continue to have nothing happen to them, rather than exciting hemorrhagic fever or Quarantine Zone.
Would that not offer obvious evidence of collusion?
Only in the limited sense that two parties agreeing to an armistice are 'colluding'. Perhaps if they agreed to a delightful cross-licensing and then started suing every non-Samsuing android OEM into the ground; but if there isn't any licensing going on it's likely just a recognition that neither side has really gained much in the litigationdrome. Apple has won some; but not nearly the damages they wanted (and they've been more or less entirely unsuccessful in actually stopping Samsung from churning out and shipping large quantities of hardware), Samsung has at least blunted most of Apple's advances, possibly won some of its own suits; but kept all very large damage claims and attempts to ban devices that are commercially relevant away.
Without a clear legal edge for either side, they could keep slinging shit at each other; but it becomes an effort in throwing billable hours down the drain while other Android OEMs continue to put pressure on prices and Samsung's attempts to pull a 'fireOS'-style independence bid from being Google's pet board stuffer continue to mostly suck.
If Apple had actually managed to knock out a meaningful collection of Samsung devices or firmware features, or even just score some settlements of the size they wanted, they'd have much less incentive to stop; and if Samsung had managed to score a win or wins that conclusively got Apple off their back they wouldn't need an agreement; but neither party has. Apple likely has (between the number of patents and the number of venues for fighting about it) unlimited lawsuit fodder; but they haven't been able to make any of it hit has hard as they would like; while Samsung has been able to whittle down Apple's demands quite substantially; but has no chance in hell of getting a 'the court has proven that Apple needs to stop suing you now' decision.
Your files are now being encrypted and thrown into the bit bucket. EOF