Your premise that WM has any chance of going away is wrong-headed from the outset. It's highly unlikely that's going to happen; SE doesn't want any part of having to balance around free mobility. Remember that their only answer to this in 2.x was to use the rubbish "but it's a support" non-argument to "justify" crippling Bard's damage output to a point where no amount of mobility gains could ever make up for it.

People who gave up on Bard after trying WM for a dungeon or two, or who don't play it at all - sure, they might think that losing WM is a good idea. The ones who currently play Bard at a high level, understand that that's not the issue at all.

The issue is that the confluence of (WM + River of Blood + lots of other oGCDs) just doesn't function properly. It's anti-synergistic and leads to a myriad of decision points that - while yes, in a vacuum more decisions means more skill - some of these judgment calls are frankly bulls**t in nature and have no place within the design philosophy of this game.

Trying to figure out on the fly whether a DoT tick that started a refresh animation that finished some variable tenths of a second later, came before/during/after a half-second window on your cast bar, and then responding appropriately within the next half second - that kind of thing belongs in competitive fighting games where people count frames, not an MMO that ostensibly uses a 2.5s GCD to allow room for forethought and attending to mechanics.

By far the most plausible route SE could take to address this, would be to overhaul River of Blood in some way. There's a semi-common expectation of some manner of charge/stack or storage system, especially with Yoshi talking about class-specific UIs. But it's kind of an open question as to how they might ultimately go about it.

And there's always a chance Yoshi was alluding to a re-focus on songs. If you recall, when 3.0 launched every Bard song save for Swiftsong came with a 3s cast, and it took a lot of pressure for them to back off of that inch by inch. I wouldn't be surprised at all if there a rework aimed at making Bard songs powerful enough to justify giving them long casts again.