The US government is not shut down. At least, it is not shut down just at the moment. The (possibly temporary) reopening lessens the economic risks and gives government employees real money that they can spend in the real economy. The lack of harmony demonstrated between the White House and Capitol Hill may worry investors looking ahead to debt ceiling issues and a September budget.
If anyone is still awake while watching the interminably tedious process of getting the EU out of the UK, this week is moderately interesting. The UK parliament votes on the government's plan B (this is plan A, cunningly disguised as something original). It is not this, but the amendments that are interesting, and which may extend the exit date until December.
Assorted central bankers are due to speak. The Bank of England's Carney (plus a whole group of backing singers from the monetary policy committee) cannot say much while the EU situation remains unresolved. The ECB's Draghi will be cooing like a dove before the European parliament.
The US has little on offer, other than speculation ahead of Wednesday's US-China trade talks. That should be enough to entertain markets, however.