I see no problem at all in there being a a second vote at the end. Clearly the government now have to investigate what can be agreed to leave, whether that involves starting the Article 50 clock or not.
At some point in the future, there will come a time when the negotiations reach a final point, and the assessment of terms at that point can be agreed,
It may be that there is no 'win' scenario for the UK in the negotiations - if it turned out that tariffs were 20%, no-one was running care home or cleaning hospitals, income tax went up 10p, a complete absence of olive oil, etc and generally things had gone to wrack and ruin, enforcing that without the electorate seeing what it would cause and accepting it would seem stupid. (exaggeration of effects to make the point only). That's what Hunt said as far as I know, and seems fine to me.