Say the authorities arrest Trump. He could face charges of bribery for the Carson endorsement. He could also face charges of inciting violence for some of his remarks at rallies, which supporters took a little too seriously. Then the GOP has a contested convention. Who becomes the nominee? Cruz? Kasich? Somebody else?
Long, long, long before an actual arrest would be Justice Department inquiries and investigations, possibly by a special prosecutor. It won’t just happen out of the blue. Trump will have plenty of warning, and so will the Republican convention.
I don’t think Obama really wants to deal with this hot a potato. The possibilities of a backfire are too high.
That would be classic prosecutorial overreach.
Arrested for a speech act? Not unless he unambiguously asked the crowd to beat to death a specific individual. And I don’t see Trump doing that.
Probably Cruz. But a lot depends on the final composition of the rules committee.
He can share a cell with Hillary, D. B. Cooper and Jimmy Hoffa.
**
Get Cruz.**
Actually, the book on which Get Carter was based was originally called ‘Jack’s Return Home’; a far better title.
Being arrested does not make you ineligible to be elected President. In fact, being convicted of a felony and serving time in prison still does not make you ineligible.
(I suspect that the founding fathers left out any such disqualification because most of them, including General Washington, could be convicted under British law of treason.)
Of course, you wouldn’t actually be allowed to vote for yourself. 
What if Hillary, Bernie, Trump, Trump’s Hairpiece, and Cory Lewandowski all get arrested?
I will admit that Bernie has been arrested. But that was over 50 years ago.
Eugene Debs ran for President while he was in federal prison. He only got 3.4% of the vote, but his total was the highest a Socialist Party candidate ever received.
Cruz could actually win the Presidency, though he might have lost in a tag-team match against Trump and Trump’s Hairpiece.
Bernie could. (Vermont is one of the couple of states that lets felons vote while still in prison.)
None of things mentioned in the OP come anywhere near to being crimes. If they were most politicians would be in jail right now. Arresting him for any of those things will swing many more voters to his side and result in some unemployed LEOs.
You also imply this will result in a contested convention somehow when it will not change the picture on that at all in itself. Arrests don’t cause contested conventions.
How many threads are you going to start that contain this nonsense? I think you’re up to at least 3 now.
A criminal complaint has already been filed against Trump alleging charges of felony bribery.
Why wasn’t Obama charged for doing exactly the same thing with Hillary? It’s because it will never be applied in this manner or we’d have thrown every president since the law was enacted in jail. Maybe that would have been a good idea, but it didn’t happen and it won’t happen here.
Trump can manage his campaign from his cell. He’d have to use a jail phone though, and the high cost of collect calls from jail would burn through much of even his fortune.
Just to clarify:
“Filing a criminal complaint” in this article appears to mean that this group has written a letter to the Justice Department asking them to investigate Trump. You or I could do the same thing if we wanted. It does not mean that any criminal proceeding has been initiated or that any law enforcement agency has found that Mr Trump did anything wrong.
I’d like to know why the OP is ignoring the equally vital (and only slightly less likely) question of what happens if Trump gets abducted by aliens.
I guess it depends on whether they’re legal or not.