We have been told for years that returns to capital are high, associated with the stronger productivity growth. For most of the late 1990s, markets certainly behaved as though that was their expectation. If it were still thought that prospective returns are pretty good, then one would be unlikely to worry about getting into a deflation trap.
It would take a pretty large, persistently expected deflation rate to spring such a trap. Of course, if there has been an excessive build-up of capital, then returns might be poor for a while, so that the natural rate might be very low during the period it takes for that excess to be worked off.