I don't know that we can anticipate more man-coverage in the future. The use of Covers 2 and 3 Zone defense has grown largely because there are so few DBs who can consistently cover the bigger, faster WRs who have entered the league in the past 15-20 years. Zone defenses are designed to prevent the big play off a deep throw.
The advantage of a Zone defense in that regard is that the DBs are able to keep some distance from the receivers, face forward and follow the ball whereas in man-coverage the CBs are blind to where the ball is going until the last second. The disadvantage of zone is that it allows some open areas usually in the middle of the field. The Tampa 2 variant of the standard Cover 2 Zone is designed to better defend the middle area in front of the Safeties by dropping the MLB fifteen yards deep. The Colts, Bears, Vikings, Chiefs and Lions have played it that way. But it takes an MLB with above average speed and agility to do it well. And it requires DB who are a bit smarter and faster, at least quicker, and who are especially good tacklers.
Many 3-4 teams like the Cows, Chargers, and Bills play a base Cover 2 Zone. The Fire Zone blitzing, 3-4 Steelers more often play zone in a Cover 3. And so have the Giants in many of their zone blitz packages under Spags.
The more teams adopt a 3-4, the more zone behind it we are likely to see. That's not to say that we haven't already seen more man coverage, as we have more recently with the Giants. But I think the main reason for it is not so much because of an increase in "pressure" defenses as it is an effort to disguise the coverage. Obviously, man coverage can be riskier if you aren't able to pressure and hurry the QB. But pressure is the objective of all teams whether they favor zone or m2m coverage based on their personnel.
The Giants have tended to switch back and forth between zone and man when playing in a Cover 2 shell ( two deep Safeties). It helps disguise their intentions both in terms of coverage and blitz pressures. In fact, they sometimes run counter to traditional pre-snap alignments. It used to be that we could anticipate whether a defense was playing man or zone by where the CB was positioned relative to a WR. If he was up tight on his man, or playing off and inside the the WR's shoulder, he probably was playing Man. If he was back and lined up on the receivers outside shoulder, he likely was playing Zone. There even was a time when he would follow his man across the field if he went in motion. But no more.
If we see more man coverage, it will be by teams who have above average cover Corners, and by more teams who seek an advantage by mixing coverage in a Cover 2 shell to better disguise it.