In my opinion, the best deal Trump will get from dems is changing the visa lottery to merit based in exchange for DACA legalization.

Changing family based migration is something democrats will not go for. You're talking about the biggest change in the immigration system (affecting millions each year)just for 800k people and it only happens one time. It's not just that either, he wants more money, change asylum laws, etc etc.

Allowing more merit based immigrants will be extremely weird. Right now the less skill jobs aren't filled but if you push high skilled foreign workers in the US, US citizens will be priced out of those jobs and they'll have to do low skill jobs or there's going to be a significant reduction in salary for high skill jobs.