Yeah, 3-4 and 4-3 seem to be going the way of the dodo. I mean, coaches still often call their schemes base 4-3 or 3-4, out of habit and tradition, but I bet if you look through their play calls, you more often see them in 4-2-5 or 3-3-5 these days. Hard to do anything less with offenses frequently/usually splitting 3 or 4 receivers out wide. Whether man or zone, that's a lot to cover--and a lot of risk deep--unless you devote five guys to it.
Even the teams that don't "run spread" are spreading the field to some extent. Consequently, 7 in the box, 4 in the field has given way to 6 in the box, 5 in the field.