I don't think there's that much to worry about. If a VC wants a liquidation preference, that's fine--they'll have to pay for it by giving me a better valuation

I don't think there's that much to worry about. If a VC wants a liquidation preference, that's fine--they'll have to pay for it by giving me a better valuation (in other words, giving me money money more cheaply). The market corrects for all of these kinds of things.