It depends. Not every country has a presenter of the calibre of Petra Mede. Apart from Dermot O' Leary, have even we?
I was just thinking that. You'd presume Graham Norton would be main presenter, but would he also have to do the commentary for the UK? In which case, I assume you'd need at least one other presenter to go through the scores and be there in case something happens.
As per the arrangement in 1998. Terry did the UK commentary and hosted at the start and end, whilst Ulrika did everything else.
I think Terry had a very unique role in the Contest to be fair, and because it was on the BBC in 1998, I assume the producers felt that not having him as part of the on-screen presentation team would have been both a bit of a snub to him professionally, and also slightly odd for a UK audience, who associated the Contest solely with Wogan. Also strange for the audience for there to be a different commentator for 3+ hours too, so I can understand the choice!
Having re-watched the 98 Contest, I would say now it looks incredibly odd to have that set-up, and I can't see a producer choosing to do that with any presenter now.
Graham Norton would be the default choice of course, possibly with Mel Giedroyc and Rylan Clarke-Neal as co-presenters. Fantasy team: I think it would be nice to see Mel and Su Perkins present (they do have international recognition thanks to Bake Off, although perhaps not so much with an European audience), with RCN in the Green Room, Norton behind the mic.
I don't think we're that far away from Graham Norton being the wrong choice for the commentator anyway. Eurovision is attracting an increasingly younger audience, and one day, the presentation team will have to reflect that. If you think about it musically, Eurovision entries are closer now to Radio 1 (non-specialist) playlists, than they are to Radio 2 in my opinion.