I'd say the main obstacle to this is the application of Salic Law, i.e. nobody except a Capetian is allowed to acceed.
The POD I usually suggest for ditching it is a Plantagenet victory in the Hundred Years' War. A scenario I just came up with involves Napoleon not losing everything, but surviving on the throne long enough to secure the succession of a daughter (OTL's Napoleon II not being born). All she needs to do is marry someone from Austria and have a son who succeeds.
In fact, this might work better if we butterfly away Napoleon himself marrying into the Habsburgs.