"Unfortunately I find it hard to believe that any nation will take on Turkey for the RoC"
Absolutely right, no one will do it for the RoC, they will do it for the reasons they have done it in the past, and it definitely was not the welfare of the Cypriots.
You are confusing the case of the Dardanelles campaign with Cyprus. There you had an invasion of Turkey, and an exclusively land based campaign by the Turks, here you have Turkey trying to maintain its hold on foreign territory. The only thing an adversary has to do it is to sever air and sea ties between Turkey and Cyprus, there is no need to defeat the army on the ground.
Think for a moment whether the Americans and other arms sellers would sell anyone a weapon that could be used against them. If you honestly think that then you do not know how these people think and act. And this should be enough about the effectiveness of the Turkish navy and air force in the event of a conflict.
And finally remember Erdoghans statement, "if they tell us to take our army out of there we will have to take it out".