There’s been almost everything from fudgets to FRP implemented in Haskell, each with their group of backers saying that approach will be “the next big thing”…and yet here we all are (for more information, see A History of Haskell ).
Since the various “revolutions” didn’t happen, perhaps an approach based on “evolution” could be made, starting with a simple foundation to which more is cautiously added over time. But in addition to time, it also requires patience, certainly more than one person or a small group could sustain.
But with the advent of the HF…“this time could be different” : a HF-backed (re)exploration of the options (or implementations) for GUIs in Haskell may have more success. But you’ll have to ask the HF about the possibility/feasibility of starting up such an endeavour.