Given the succession of nations, some far less suitable/ready than others, which have joined the EU over the last decade or two it beggars belief that anyone would think Turkey won't, sooner or later be admitted. A deal will be done because Turkey in the EU is what the EU wants. It's not what we should want but that probably won't stop our govt. being complicit in one way or another.
All this guff about 'tough conditions' makes me laugh - would they be conditions like those which allowed Greece and Cyprus to join the club? That went well didn't it.
The EU has plenty of previous for moving the goalposts to suit itself.
As regards visa free travel - I'm sure the plethora of secure borders throughout the EU will ensure that Turks who enter the EU all go home when they should and won't at all wind up within the black economy and later seek asylum under ECHR rules.