The thing is, for us Europeans, there are very few companies that offer good ETF's.
As you will know, the US Domiciled ETFs carry a 30% withholding tax on dividends, which sucks.
I am personally invested in iShares and UK Vangaurd.
I would estimate the chance of both of them liquidating in the next few years is low enough for me to not have to worry about it any time soon ;).
..Aber als Berliner ick werde sowas sorgenlos denken, wa? :P