GS asked the question and Trump said it might be a good idea, since he has standing. We’re all better off if the issue is resolved before the nomination. One would think Senator Cruz would want that, too, especially since he’s a conservative who respects the rule of law and Constitutional governance.
The ONLY way the issue will be "resolved" and "cleared up" to the satisfaction of Trump supporters will be if Cruz drops out and mindlessly throws his support behind Trump. Anything short of that, and numerous pro-Trump conspiracy theorists will continue to post "evidence" on the internet that Cruz is "ineligible" and "not a natural born citizen", regardless of what anyone else says or does on the matter.
The courts want to duck it if they can.
They dropped the ball on Obama and for all practical purposes have changed the definition of natural born citizen.
Cruz is eligible if Obama was and they will find it that way if forced to.