I agree 1000% with you on that! Michael Eriksen (stepping in for Roy) laid it on us at Prog Power last year and I have to say that NO ONE was disappointed with his singing ability! He stepped in on short notice, but his performance did not reflect that.
I've seen the performances from Fabio, but his voice just doesn't fit with the vocals.
Indeed, from the one live clip I saw below of that show I am so sad that I wasn't able to go.
Michael did an amazing job, and with only 3 days to rehearse for the show, phenomenal.
I agree with you, I've watched the Fabio performances and I have to stop watching, his voice does not suit anything from Kamelot.
The only other person I could see replacing Roy, would be Tommy from Seventh Wonder. Tommy has an amazing voice range, just like Eriksen. I have to add though, in no way should it interfere with CM's or SW's own music. Those two bands are way too important to the Prog Metal scene to disappear.
I've actually never listened to Seventh Wonder, someone posted some videos of him stepping in for Roy on tour but the audio was so horrible you could not make out anything.
I asked for anyone to post some links to some of their best stuff so I could get a feel for what it would be like for him singing Kamelot, but no-one ever did.
The other vocalist I was thinking of is Chad Barnes from the American Progressive Metal band Draekon, he has a phenomenal voice that is eerily very close to Khan's, Roy Khan is one of his inspirations and he is a big Kamelot fan, so go figure.
He even recorded a cover of Karma with Greek Power Metallers Orion's Reign and does a lot of Kamelot covers. You should check him out and his band.
I also agree though, in no way should this interfere with their primary band commitments.
Ultimately, I am hoping for a Khan reunite (if he ever gets over whatever is afflicting him to the point where he can take the grind again) and then all of the speculation can go away. 
