I wouldn't say we would definitely lose. It wouldn't be a shock if we did when you see how similarly rotated teams have fared in the Carabao Cup, but i think there's enough individual quality there to remain competitive and give us at least a chance of a positive result. And at least all those players should in theory be looking to impress and force their way into the established first XI. If we took a few genuine first teamers there's little incentive for them to do anything but coast through the game avoiding injury which rarely helps matters.
Going much weaker than than and genuinely playing 'the kids' would open us up to a lot of grief from Napoli, UEFA and the media we could certainly do without. But even UEFA couldn't find a way to fine us for "only" fielding a team containing Aguero, Gundogan, Bernardo, Yaya, Danilo, Mangala and Bravo.