I think the Europa League could be a blessing in disguise for the start of Pep's tenure.
Even if we finish 4th, Pep will be expected to win the CL and a huge amount of pressure will be added onto the side. No thought of a transitional season will be mentioned in the press and we will be under fire to perform on all fronts.
At least in the EL, we will know that the PL is our priority. Give players like Denayer, Iheanacho, Angelinho and Manu Garcia regular starts in Europe and see if the latter two can make a case to be in the 1st team.
Don't forget the likes of Sterling, Kane and Rashford only got a look in at their clubs because of the Europa League.
The in Pep's second season his players will have settled and the club will be ready to push on for the CL.