It just cuts the effective key size in half.  The current 160-bit signatures will be brute forced in 2^80 operations.  That sounds weak, but it's going to be a long time before quantum computers reach 160-bit levels (if ever), and even when they do the operations per second will be very low and 2^80 will be infeasible for a long time thereafter.


The OP was talking about ECDSA, though.  There's certainly a chance that a weakness will be found, but there's no expected timeframe for that.  It's not a case where increasing computer power will break it in 5-10 years.