While I have a multi-gigabit domestic service myself, it should be noted that current peak usage averaged over a home user base is not much over 10Mbit per subscriber. I wouldn't expect that to grow past
Openreach, sadly for us enthusiasts, have determined accurately that the maximum return on investment comes from GPON at the moment as it meets the vast majority of domestic customer needs.
The only place they are likely to feel competitive pressure for higher speeds is from VM, I suspect that is the driver behind the 1200/120 and 1800/120 products. They've done enough to stay competitive until VM's XGSPON is widespread and the premium segment demands services greater than 2000 down. The first will take a while, the second will take longer.
If you take generous estimates of 15Mbit current average peak and 25% sustained year on year growth, average peak doesn't exceed 100Mbit until 2030. Openreach can still support that on 32-split GPON.