It will be interesting to see if any other countries follow this idea. I imagine the Australian parliament could create a few electorates that way (one in London and one in Dubai, at least, with perhaps smaller seats representing agglomerations of Berlin, Tokyo and so on). If one thinks cynically of the gerrymandering aspect of this, it could profit the US Democrats to try this, given the fabled liberal leanings of Americans with passports.
If ex-pats start receiving representation in Parliament, it raises the interesting question about taxation --- do ex-pats pay taxes? I should remember, but don't. If you don't contribute, but still get a say in the way our tax dollars are spent ...
Only a few countries require their expatriates to pay their taxes; the USA is the most notable among them.
However, expatriates of most countries do get to vote; it's just that they don't get special electorates.
Do any countries restrict the vote to tax-payers?
Theoretically, the US. Though from what I've heard, they don't make much of an effort to track down expatriates and get tax money out of them.
Does Italy do something like this?