I think KLM have done a CBA on this. They must be losing money at the rate of 2-3 CFM56's a day. So put a plane up and see what happens.
If it trashes the engines, so be it; now we know.
If it flames out, they're at FL380 and can do a power off landing anywhere within 150 NM. That might sound a bit challenging to those not used to that maneuver, but its actually not that tricky - if you've done it before. Any military pilot/UN/ICRC pilot is used to doing them in high threat areas. Mind you, I'm not conversant with what the B737 they've chosen for the job can do if it flames out on both and the APU chokes as well. Manual reversion? Keep the gear down as a precaution? Some fluffy driver jump in here.
There's a lack of hard data here and that void needs to be filled urgently. The Finnish F18's do not make it seem likely that it will be a positive outcome, but for the sake of the industry we have to know. And two engines is a cheap price to pay given the alternative. Desperate times mandate desperate measures. Kudos to KLM for leading the way.