Statistics says when there are a number of mechanical issues, with the only car in a garage, then the driver is out from the team by the end of the year.
Take a look: 1) MS at 2006, 2012 (No problems for Massa and Nico) 2) Coulthard at 2008 (No problems for Mark) 3) Barricello at 2009 (No problems for Button) 4) Vettel at 2014 (No problem for Ricciardo) 5) Vettel at 2019 ???