I'm not sure actually... when you look at the last four or five Grand Prix it seems reliability problems, not just the terminal ones, are accumulating for Mercedes, and we're only just at the halfway point.
At this stage of the season engine and gearbox reliabilty are bound to become more critical, and we haven't even gone to the real power circuits yet like Spa and Monza.
It maybe that one or both drivers will experience some kind of reliability problems at most week-ends for the season's remainder, so there's no reason think Nico will be spared them anymore than Lewis. It could all change very quickly...