Happy to help! That is nearly correct. Once you make the election it continues until you revoke it. Once you revoke it, neither of you can ever choose to make the election again, either together or with any other spouse. To revoke it you file a statement with the IRS containing specific information outlined in IRS Publication 519 And yes, if she meets the requirements to be a resident in the future, then she will file as a resident at that time.
However, the election may be suspended for certain tax years if neither spouse is a US resident for the entire year (ie. you abandoned your citizenship and residency). Also the election is terminated if the marriage is terminated, or if either spouse dies (in the year following; it remains in effect for the entire year in which the death or divorce occurred).
One additional detail. In the year you make the election you must file jointly, but in subsequent years you can choose to file separately if needed.
