First, do I really want to live in the US? I guess the kids may want to stay here as they have the friends here. It's prudent to say it's highly likely that our primary residence will remain in Bellevue for the next 10 years.
Second, what will happen after 10 years? I guess being a US citizen, we would have more freedom to choose where to go and live our life. So maybe it's still an advantage to naturalize to be a US citizen.
Another benefit is that I can get green card for my parents earlier. So they can spend more time freely in the US. The downside is that there will be tax complications regarding the investment income.
Today I spent quite some time to ponder on this question, and here are my conclusion.
Ariel should naturalize to be a US citizen this year.
It gives us a way to stay here safely. In the long term, it's highly unlikely we will move back to China. There will be so many aspects of life that we can't get used to.
I will wait until I get rid of all real properties under my name.
There will be tax consequenses otherwise. Also, it's tricky to sell the property if it's owned by a foreigner.
The risk level for a tax audit on Grandma is low at this moment.
Because the accounts are not reporting to the IRS, there is no reportable income for her even if she qualify as a US tax person.
However, we need to be careful in sending money to Grandma in future.
The amount of money that we sent out every year to each individual should be carefully limited to minimize the risks of violating the gift tax rules.
There is no hurry to get green card for the grandparents.
First, they need to get rid of a lot of assets in China. It's too much work and too much risks to operate flawlessly.