I wont call them "predictions," but I want to put a couple of conjectures about the events of 2018 on the record now, so I can claim astounding prescience later.
Donald Trump will Resign the Presidency before November, 2018
More specifically, I expect him to resign sometime between May and July 2018, having received assurances that Vice President Pence will use the pardon power and other powers of the Presidency to protect Trump and his family from further investigation and potential prosecution. This will be sold to the President as a strategy to pull the rug out from under his opponents, to cement his legacy, and to say that the new President is his hand-chosen successor.
If the President does not agree, Vice President Pence, Speaker Ryan, and Majority Leader McConnell will rally the Cabinet and Congress to, regretfully, invoke the 25th Amendment due to the President's deteriorating "health."
In either event, the Trump Administration will end three to six months before the mid-term Congressional elections. (Acting) President Pence rallies evangelicals and Republicans who have grown tired of apologizing for the disgraced Game Show Host in Chief. GOP losses in the House are safely limited. Crowd goes wild.
Russia Investigation Part 1: Keystone KGB
By the end of 2018, there will be sufficient information on the public record to construct an accurate narrative of the Russian government's activities related to the 2016 election. It will be a mess. We will start to distinguish between amateurish personal initiatives -- like the Russian State Prosecutor's effort to do some kind of deal with Don Jr. -- and the activities of the GRU (Russian military intelligence) and the SVR (Russian foreign intelligence). The intelligence services will turn out to be more organized, but frequently at cross-purposes with one another. Ultimately, we will understand the Russian "initiative" as a motley assembly of shady characters trying to put one over on the collections of dimwits and half-wits that constitute the Trump inner-circle. Most of them will turn out to have succeeded.
Russian Investigation Part 2: Hey, where'd my money go?
Listening to Donald Trump giving interviews, in the White House or back on the campaign trail, who among us has not thought, "How is it possible that a guy this clueless hasn't been robbed blind by his business associates?"
I offer this conjecture: it is not possible. And, as somebody wise -- Einstein or possibly Basil Rathbone -- once said, once you have eliminated the impossible, what remains, no matter how improbable, must be true. Which is to say, any serious inquiry into the finances of the Trump Organization will reveal that somebody has made off with all of Trump's money, leaving debt and worthless paper behind. Robert Mueller's money-laundering investigation would count as a "serious inquiry," by the way.
Sooner or later, someone is going to tell Trump. Hijinks ensue.