However they have already shown very clearly that they aren't like that. Given the total absence of compromise previously I see no reason to expect any now, unless quite a few of the current leaders of the Commission and EU countries are removed.
The EU will use whatever tactics it can to preserve its own power, national populations be damned.
Nowadays, not so much. Perhaps that's Juncker, or perhaps it's the fact that it's now so large. See how Cameron's negotiation went (or rather, didn't).
Besides, most of the compromises were simply not forcing the UK to do new things. That's only seen as a compromise because the EU is run by people who believe every member should be forcibly 'harmonised' through automatic implementation of new EU laws. If the EU was more like a standards body that simply recommended laws instead of mandating their implementation, there would be no need for allowing alternatives to be seen as "compromise"
There would be no point in an EU that couldn't mandate laws.
Suffice it to say, the EU could have taken many structures that are not the one it has now.
The problem for the UK is that they always want have all the benefits but they don't want all the duties.
I doubt any trade agreements the UK might be able to get, would be worth the backlash of turning the EU into an enemy. Especially considering that anyone the UK would want to trade with, probably doesn't also want to harm their relationship to the EU. That last point alone probably ensures that nobody is going to start trade discussions with the UK anyway until after they leave.