Good chance with the Mercedes deal that they will be the 4th best team on the grid.
reason I say that was because I remember that with Mercedes for them 15 or 16 years they were always competitive. always winning & challenging for championships. looking at the stats mclaren won a race in every season from 1997 - 2013 bar 2 seasons 2006 2013 but really only 2013 was the failure because they had 3 poles & 9 podiums3 drivers championships and 2 constructors titles in 15 years? Not much of a byword.
They left because they knew the parent team would not let them beat them. They were right and still are.