No you're not paranoid. It's understandable to be worried, but coins have been faked for a very long time. What's different now, as you rightly allude to, is that the quality of the fakes makes them difficult to spot. There's some coins which have been faked for a long time, such as the 1905 shilling and halfcrown, some of which are tooled versions of other legit coins from different years. As far as I can tell there hasn't yet been a significant effect on values.
As to how the future will pan out in this regard, I don't know, and if they're being honest, nor does anyone else. But let's not forget the scope of coins across the board, is huge, and the Chinese haven't a hope of tracking the lot, or even any more than a minority, and faking them. To do an effective job, they have to specialise, and the very fact that a fake Kew Gardens 50p has come to light, means they will be found out, however good they think they are, or seem.