I would say that there is a current shift towards more ‘liberal’ policies in some areas, but not in others.
But regardless of what’s going on today, I think trying to do a straight-line extrapolation into the future is folly. Countries often go through phases of liberalism, followed by phases of conservatism. France seems to be undergoing somewhat of a conservative transition right now. Look at Britain - from an almost socialist state it became quite conservative for a couple of decades, and now seems to be trending liberal again.
It may simply be that as the country starts adopting liberal policies, it gets to the point where taxes are too high, unions have too much power, government gets too controlling, and then the population rebels and starts electing conservatives to restore some sanity. Then if the country trends too conservative, people rebel against that and start electing liberals again. I don’t know why we need to believe that there is some long-term trend taking us to a liberal utopia. For those of us who believe that liberalism just leads to stagnation and an overly-controlling government, there’s no utopia in the end, and as things get worse the pendulum will swing back the other way.
Thinking about specific issues in the U.S., I’m not sure I’m seeing a big trend towards liberalism anyway. Sure, most people say they want a Democrat to win the White House next time around, but that could be simply a reaction to their dislike for the current crop of Republicans, not a desire to see widespread adoption of liberal policies.
Looking at specific issuss, I don’t see a big demand for a resurgence of the welfare state. Raising the minimum wage had a lot of support, but such things always have support when people think it won’t cost them anything. When unemployment is as low as it is, and average starting wages are already much higher than minimum wage, raising the minimum is little more than a feel-good policy.
Gun Control seems to be completely off the table - an area where Liberals utterly lost the battle. Not only are they not getting new controls put in place, but the old ones are being actively repealed. Concealed carry laws are still increasing. The ‘assault weapons ban’ is dead.
70’s style welfare is dead and not coming back. I’ll bet you that support for increasing welfare in general is in single digits.
The increasing support for liberal policies seems to me to be mainly in two areas: Health care and the environment. The Republicans are not on the same side as the public on those two issues, and that’s driving their popularity down.