There should be no need for a guarantor or guarantors.
One hopes that the majority of people on the island have grown up since the 60's, are not typical of many members of this forum who are so full of hate and have the inability to accept that everything is not the fault of other countries but was of their own doing, are not stuck in the past and going on about murders and rapes that happened from 34 to 45 years ago.
Atrocities were commonplace during WW2 but did the people of more foreward thinking countries continually dwell on the past? No they didn't. The ones in Europe got together, became friends, formed NATO and worked successfully to a better future where they would never again kill each other.
The world will shortly know whether Cypriots belong in a better world, whether Cypriots realise that they must make painful concessions in the current negotiations and bring them to a successful conclusion.
If they can there should be no reason why a united Cyprus, a two state Cyprus or a federation should not join NATO. Conscription into the army in Cyprus would no longer be necessary but with small professional units of soldiers Cyprus could also play a useful part in NATO operations.
Incidentally I believe that Turkey no longer needs a military presence in the north as GC's would, in the modern world, never again behave as they did towards TC's during the period from 63-74.