Trump hasn’t cancelled flights from the Uk, just from the schengen area. Which means anybody from mainland Europe who wants to go to America will travel through the UK first.
You won't be able to fly through the UK to the US from the Schengen area - the statement they issued makes that more clear.
www.dhs.gov/news/2020/03/11/homeland-security-acting-secretary-chad-f-wolf-s-statement-presidential-proclamation
Today President Donald J. Trump signed a Presidential Proclamation, which suspends the entry of most foreign nationals who have been in certain European countries at any point during the 14 days prior to their scheduled arrival to the United States. These countries, known as the Schengen Area, include: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Liechtenstein, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, and Switzerland.
This does not apply to legal permanent residents, (generally) immediate family members of U.S. citizens, and other individuals who are identified in the proclamation.