The deal certainly won't be as good as full single market membership, that much is for certain, but I think we can safely discount the idea that an FTA is totally impossible as pretty out there - South Korea and Canada have one and the UK already has the exact same regulatory standards as the EU by virtue of being a member for the next 2 years. Free trade in goods seems very easily achievable, services probably much less so but the similar regulations probably help in this regard vs the Canada deal.
Of course this will require the UK to keep to EU regulations for any goods destined for export with all this which is why Brexit is dumb. At least the PM acknowledges this now.
Of course making free trade deals with the UK is much more simple on account of all that. I also see no reason that once it is left that countries would not jump at the opportunity to do so. Making deals with a desperate partner is shooting fish in a barrel and on account of their existing stability, none of these other nations have their success predicated on making these deals, for them it is a nice value-add.
This is completely overstating it. They don't want failure, because they'd still theoretically want to sell to the UK. However, they do want to extract a price on leaving on account of political realities.you are completely discounting the political dimensions here. EU wants UK to fail. they will take the economical hit and hope that the hit is harder for UK. why? because otherwise everybody will want out of the EU. france, netherlands, austria are already lining up