Three weeks, then we get this insanity again.
Right, this all part of the theater. With most of the "deals" that Trump has signed as president, other parties had to negotiate something and then take it to him and convince him it was politically favorable for him to back it. He's generally not been involved in any actual negotiating.
So one interpretation of today's event is that someone, probably republican senators, went to him and explained that he was losing this fight badly, and getting worse by the day, and that stalling while doing nothing was only going to make things even worse. He desperately needed to shake things up somehow, because Nancy Pelosi was grinning ear to ear as Trump's shutdown got worse and worse. So this three week deal imposes a new deadline, and it refocuses blame on the new "bipartisan commission" that is going to negotiate. Now it can be their fault instead of his, and perhaps they convinced him this was the best way to protect himself from the consequences of his bad decisions.
As an added bonus, the announcement to temporarily end the shutdown splits media attention away from Trump's personal involvement as the connection between his campaign and Russia, as the one who personally spoke to Roger Stone about his contacts with Russian military intelligence officers posing as online hackers. Stone's indictment totally discredits Guiliani's defense that only Trump's people colluded, but not Trump, and Trump didn't know about it. Turns out Trump personally colluded, in his talks with Roger Stone.
But a second less charitable interpretation of today's shutdown announcement is that Trump caved way harder than he had to. The democrat's proposal was to reopen government for three weeks in exchange for 12 billion dollars of funding for border security, and he turned it down. Then today he agreed to reopen the government for three weeks in exchange for... absolutely nothing? He could have gotten a better deal than this two weeks ago if he had just agreed to the democrat's proposal in the first place.
I'm eagerly awaiting the savage whipping he'll get from Ann Coulter and the rest of the alt-right media.