Hmm. In my mind there’d be a few challenges.

One, transmog is launching with only in-game learnable motif styles. You still can’t make Varen’s unique stage, for example. But down the road they could easily enough add transmog skins you can’t necessarily craft. In theory they could even open skins tied to achievements...you kill a boss and get a specific achievement, you can transmog their unique weapon. But I wouldn’t expect such an update for quite a while. ZOS isn’t known for making major updates to existing game systems...consider that justice, Homestead, etc are relatively the same since they launched.

Two, character animations are a big hurdle. The bows have to be designed to use the same animations regardless what style they are. A crossbow couldn’t do that.

I’m going to guess that we’d be more likely to see crossbows introduced as a new weapon line (which also feels unlikely) than see them appearmas transmog skins.