Ideally I'd love to see FR for DUB, AGP, and ALC, with KL for AMS.
KL does rather well at Humberside, and can bring in a lot of business and VFR pax for onward destinations from AMS. If they can make HUY, MME, NWI work on multiple daily frequencies, I have no doubt they could do the same at DSA.
Load factors for BE routes were always high, but it depends on the overall yield they were generating. Airlines with a lower cost base (eg. FR) could certainly make some of those routes work I'm sure. FR has bases in DUB, AGP, ALC, FAO, PMI, BCN etc. and could possibly make a NCL style situation work without needing to base crew or aircraft at Doncaster.
Could sound like pie in the sky though.