For Democrats taking stock of these developments, I have some piece of advice.
Who cares what Republicans think? Establishment Republicans have just had their party wrested away from them. For the moment, they are falling in line behind power. It is a mistake to quibble about 'conflicts of interest', or wait for Republicans to raise objections, or say there will be complications or things that need to be disclosed or resolved. When someone is robbing the bank, we don't explain that you can only withdraw your own funds, we try to catch them. If we can't catch them right away we try to rally others against them. There's no time or point in a charade about some inexplicable misunderstanding.
Just fall back, say what's happening and start running against it. Trump is approaching the presidency like a typical crooked strongman, shaking the country down and using the presidency to make a fortune like the bed of gold Smaug slept on in The Hobbit. He's said as much. In an aside in his editorial sit-down with The New York Times, Trump conceded: “The brand is certainly a hotter brand than it was before [post-election]. I can’t help that, but I don’t care.”
Few conflict of interest rules apply to the President because questions surrounding the President are inherently political. So stop warning, complaining, pointing out ethnical challenges. Just accept that this is what he is and will do and start running against it.
If Newt is right and we're stuck in the pre-Trump era where we fuddy-duddies don't understand that state-looting and kleptocracy were the new America, at least we will make clear that this was a change we disagree with. But I doubt Americans have changed their minds about looting the public fisc or using the presidency as private property to be monetize. Trump is historically unpopular on entering office. Presidents do not usually get more popular over time.
Stop disputing and warning. Accept that this is what Trump and the GOP wants. The answers aren't regulatory or with ethics experts. It's with politics. That is at it should be. They've made their choice, make them own it.