It would indeed be very City-esque for that to happen. Or even to make the final and our own new manager knock himself out of the CL. That would be very typical City fortune.
I can see the argument about going for the league and not playing our best players in Europe to guarantee pot 1 in the CL the season after next.
Two big problems - though - with your thinking.
One is that unless we win the Europa our European coefficient would drop a lot from basically throwing the season in Europe. That would impact the future. As would the loss of income from not going far in the Europa which is already a seriously poor relation of Champions League income anyhow.
Secondly, Pep will be signing big players and I do not think he would be wanting to tell these (hopefully) big names and our own long term CL players that they will not be getting any European football next year as we intend to play the kids instead and get them just to win the league as fast as possible for CL the next sesason.
Yes Europa would give the chance to field some kids but we have to wonder as to how much basically not playing our first team in Europe at all would impact on some of the players we might hope to sign this Summer.