BTw won't do XGS tiers by 2030, it will be a long wait! EE isp are likely to sell it first.
That is merely your opinion, which is, perhaps, as unreliable as it has always been.
I really don't care about 1600 on GPON; even if it were available to me, I doubt I would have paid extra for it. It's fairly difficult to saturate a 900 (actually a bit faster) downstream, and 1600 offers no upstream speed boost over 900.
I care about greater upstream speeds. Unfortunately for me, Zen does not have network presence at my Openreach Handover Point, so my Zen connection is via BT Wholesale. The only possibility of non-Openreach FTTP in this area is Virgin Media's Project Mustang, which is not a wholesale network. I have a low-speed Virgin Media HFC connection as a backup on a dual-WAN router and as a prerequisite for Virgin's TV service, but I do not like Virgin Media as a company, especially their ridiculous price rises, so I might switch to Sky Stream and reduce Virgin to the cheapest broadband-only deal I can get from retentions.
All this means that I care about Openreach XGS-PON over BT Wholesale. This area was only FTTP-enabled earlier this year, so, bearing in mind that Openreach have been installing Combo-PON OLT cards for a while, it is possible that our PON is already XGS-PON capable. Perhaps the rollout of 100G Cablelinks (supposedly not entering trials until next May) and faster speeds will finally give an economic justification for Zen to extend its network to all the remaining unserved OHPs, including ours - only time will tell. Maybe BT Wholesale has a catch-up plan that will cover both 1600 GPON and XGS-PON in one big leap forward, but if not, we will remain limited to whatever BT Wholesale supports.
I also think we need to keep our expectations low for Openreach XGS-PON. Unlike most altnets, Openreach makes a fair amount of money from their Ethernet products. Some Ethernet customers may be tempted to drop their leased line in favour of symmetric contended XGS-PON if they can save a lot of money, even though they would be giving up their SLA and guaranteed contention ratio. I doubt that Openreach's wholesale pricing on symmetric or near-symmetric contended XGS-PON is likely to be anywhere near as low as the altnets.
To be honest, while I have a 2.5 Gbit/s wired LAN (with a few 10 Gbit/s ports) and channel-bonding-capable Wi-Fi 7 access points, 900 is the sweet spot right now for those who want a fast connection via Openreach FTTP, and I doubt I will upgrade to XGS-PON until I can do so at minimal additional expense. As I am on the Zen £39/month promotional pricing for Openreach 900/110 until my post-FTTP-upgrade minimum contract period expires in mid-2028, I would not be surprised if I stick with 900 at least until the end of the two years.