Burn it
If they do bid and regardless of what the bid may be, they can keep Christie and Hayes.
A few random thoughts from me.
I would be amazed if McKenna was anywhere close to being Plan A for celtic to sort out their defensive issues. They would be far too arrogant to think a 22 year old from Aberdeen would be a Champions League level player (where their mindset is). That's not to say they won't work their way down to Plan Z and ultimately bid for him on 31st August once all other decent players have turned them down.
If they do bid it will be a stupid low bid and just watch their friends in the MSM talk about how it is such a fair offer etc etc to try to ratchet up the pressure on us (like they tried to bully Hibs for McGinn). No way they will bid £5M+ given they have no CL money this season
If and when we do look to sell McKenna (and any other player for that matter) we badly need there to be more than one club interested (look at how quickly celtic upped their offer for McGinn once AV put in an offer that Hibs wanted) and ideally English clubs given the monopoly money they use down there
We always have been and always will be a selling club (like every other club in Scotland including celtic and sevco) and also in fact 88 out of 92 clubs in England as well. Nothing wrong with that and actually a nice problem to have. What we have to be so much better at is the timing of selling good players and the price we hold out for (like Hibs have been over the last number of years)
Our strategy should be built around bringing through young players and scooping up other good young Scottish players like McLean/Fergusson with a view to getting benefit from them whilst they play and a good price once they move on (and a proven path to more money in England to attract future players). We need to be banging the drum that its a waste of time these players going to celtic/sevco as they will never get to play in the big games (only 6 out of 36 players in their last European games were either brought through their youth system or bought cheaply from other Scottish clubs - versus 7 out of 18 in our Burnley game)
Just out of interest, as these things are traditionally quite important in Scottish football. Does McKenna support one of the @rse cheeks?