Unless you are an aerospace engineer or pilot I don't think you can judge the quality of a plane under the surface. I note the leg space and if the plane is noisy or shakes much.
In any case, even if 10% of people totally stopped flying on Boeing, which would be a wildly optimistic outcome for any organized consumer action, the airlines would just discount those flights ever so slightly and the other 90% of price-conscious consumers would immediately take up the slack. Nobody's going out of business in that scenario. This is, of course, why we rely on regulation rather than consumer choice to ensure safety, and why this is a failure of regulation, not of the market.