I think it's fair to say that Harry Reid isn't by inclination or temperament a big fan of filibuster reform. That's partly because it will upset whatever collegiality is left in the Senate and make it really hard for him to "run" the Senate. But he's not above keeping it in play
as a negotiating chip with Mitch McConnell over important White House nominations. That's why Reid keeps raising the prospect of doing something on filibuster reform, after initially declaring the issue resolved with some minor rules changes in January. His threats make a lot more sense in that context, especially since it's not clear he has 51 Democrats on board for a dramatic rule change. But McConnell probably knows that, too, so at some point this posturing will lose his effectiveness, if it hasn't already.