My wife (English) and I (US citizen) have been living in Canada for the past 3 years. Before that we lived in the US where we were married 20 years ago. My wife holds a green card (and for the time being a re-entry permit that we applied for during a visit to the US, which will soon expire). It is our plan to return when my contract here ends after 5 years, but aside from some bank accounts and retirement funds we do not own property in the US.
When we return to the US from time to time to visit my family I am afraid that the border official will determine that my wife has abandoned residency in the US. At least one official has threatened to do so, but backed down.
My question is whether it is better to turn in the Green Card now or to take the chance of it being confiscated when we drive over the border. We know we plan to return in the end so keeping the Green Card would be very useful. If she is determined to have abandoned residency what can happen? Will the Green Card be confiscated and she'll be turned back at the border? Is there the possibility she'll be detained or deported (with exclusion as a result)? What impact could this have on her getting a green card in the future?
It seems moronic (and expensive) that the best way to be able to return to the US safely after 5 years abroad is to officially abandon resident alien status and have to go through the process again. Is this right? Is there no better way?

