That's my fear as well. The last wall to topple is a straight tax on capital. Sure, they'll sell it as a tax on the uber rich just like they did with the income tax, but that threshold will drop drop drop until the middle class is paying out on both ends: tax on earned income + tax on everything you have. Every year.

As a US-er, everyone I've talked to regards me as overly cynical, but I think about Roth IRAs and to some extent all tax-advantaged retirement accounts the same way; that money is a fat target once it becomes politically expedient.