Good point. Paul made it clear that where there is no law there is no sin. He further made the point that Jews are under condemnation because they have fallen short in their observance of Torah and Gentiles are condemned because of their rejection of the general revelation of God in nature (a form of law). It seems that the primary function of law, which God created, is for the condemnation of mankind.
There's also precedent for God changing some of the laws. He has changed the dietary laws a few times.
first He gave only plants. Then He gave all animals after the flood, then with Moses, He restricted some animals, and restricted wine from priests and nazarites, nazarites couldn't even eat grapes.
Then after the new testament He lifted the dietary laws and pronounced all 4 footed beasts clean, and Paul said not to burden the gentiles with the dietary laws and circumcision.
some laws I think will be impossible to break, like Murder will be impossible to do.
some laws I think won't come into mind to break, like stealing and coveting if God is freely providing and you're not left with unmet needs and desires.
Adultery will be impossible to do because there's no marriage
I don't think idolatry would be an issue when you can see God face to face and know He's the only God.
and many ritual/dietary laws could change
So that leaves things like lying, fornication, drunkenness/intoxication, dishonoring your mother and father, and taking the Lord's name in vain.
Taking the Lord's name in vain is.. to claim the name of God, IE claim you believe in and worship God, and then do something that makes Him look bad, like do some other sin. (as given in Proverbs 30:9, being known as a follower of the Lord and then stealing because you're poor, takes the Lord's name in vain).. or using His name irreverently. I think in the first case since we're no longer having to be an ambassador for an invisible God it'll be impossible to make Him look bad because people will see for themselves His character and not have to judge it by the actions of His people.
Lying.. people do that for self gain, and the chances of being caught.
If the chance of being caught is 100%, nobody would risk it.
Drunkenness might just be solved by making us no longer susceptible to mind altering effects of drugs and alcohol, the biology would just be different. If you can drink as much wine and beer as you want and never get drunk.. well.. I don't think there'd be a law against drinking alcohol (as it is there's not, there's just a law against getting drunk)
Fornication.. there's 2 ways this can pan out. Either we have the anatomy of barbie and ken dolls, making it physically impossible to do, and I don't know if that'd be frustrating or not for some, I mean I think I wouldn't like my resurrected body to be LESS than it currently is but who knows. But.. that doesn't necessarily mean people wouldn't think about it in their thoughts..
Or since we are all technically in the same marriage, it's no longer considered fornication.
Point being.. if you have it all as just being willpower, then it's not free will, free will involves being able to make your own choices freely.
So to have free will but not sin, that means none of the choices you can make, are sinful.
and that can be accomplished some ways, namely, the sinful choices become impossible to do, and secondarily, some laws may change so that the choices are no longer sin.
I don't think we'll be actively observing 600+ laws.