I'll be honest, I've not used the Oxford Tube beyond Thornhill to Gloucester Green but based off what I have seen on tracking and on many videos which people post online on Youtube, the issue with the Tube is the journey times can be so variable so they have to set the journey times as so long because some days they'll need it, other days they won't.
And the problem with setting long journey times is, as you've mentioned on other threads, an issue because you then have to wait for those timings. If my experience with commuter coaches is anything to go by, regulars will know, and adjust their timings accordingly, almost ignoring the timetable.
Getting out of Oxford is scheduled as 30 minutes which equates to an average speed of 9 miles per hour. Same for the average speed within London. It's not the fastest and has too many traffic lights and not enough bus priority.
There are extensive bus lanes between Thornhill and St Clements - the issue is coming up to The Plain, where the road is barely wide enough for two lanes, let alone any bus priority, and around Oxford City Centre. I can't remember how the coaches used to be routed before the closure of Queen Street (I think they've always gone the long way around to Gloucester Green?), but remember Oxford City Council is already actively unpleasant towards car drivers.
The fact the journey times can vary by upto an hour depending on the time of day really shows just how bad the congestion is. As soon as you look on tracking too, it's clear that congestion can vary so much and the timetable seems to be mostly based off best case scenario so even in the peak, there can be larger delays so journeys take 3 hours end to end. It's really bad and I would like to see both Oxford Council and TFL look to start some kind of proper bus priority to speed up the Tube service.
There are roadworks on the A40 at the moment and a temporary speed restriction, which were the only cause of delay to my journey.
My only concern is will the services continue over the next few years. Go Ahead used to run coaches in competition with Stagecoach, and ran them for many years, but have now pulled out presumably because the market is shrinking. We always thought that the Kent coach commuter would go on for ever, but it is now a shadow of its former self - The Kings Ferry stopped all of its services with only a month's notice.
Quite possibly, but they've taken a sensible move rather than trying to carve it out. Oxford Bus (OBC) do airports, Stagecoach do London. Remember that the Tube has just had brand new coaches, albeit delayed through the pandemic, and at -19- plate, OBC's Tourismos are still fairly new as well. The story with Kent commuter coaches is rather different, as they only had the commuter market, whereas Tube has leisure travel too. (*)
I have wondered. One of the key reasons for its existence was that the rail service was, to be blunt, garbage. Not only is it substantially improved, but there are two competing options. Plus there's reduced commuting.
What are loadings like? Are there enough tourists to keep it going, either in its current form or as a less frequent, advance-booked service? (I'd say Megabus had Stagecoach not planned to sell it).
As we've said upthread already, whilst the rail service may have been the start of the service, it is not now the end. Many people, in East Oxford particularly, are not going to go 20+ minutes in the opposite direction to the station, they'll "turn right" and drive down the A40 instead.
Tube doesn't have loading figures, but as I write, there's an airport coach on the M25 with 41 seats free, the previous service is waiting time at Heathrow T5 with 25 free, and the coach just arriving into oxford has 24 free. To Heathrow, one coach currently has 33 free, and to Gatwick 38, 35 and 30 free. I don't know the Tourismo capacity offhand, but that's the majority of coaches over half full, which doesn't seem bad for off-peak Wednesday. (It's at least 54, because the coach waiting at Heathrow Central for the 17:05 departure has 54 free)
(*) Just a brief note to avoid going too off-topic - don't intend to develop this further: before Covid, Kings Ferry ran ca. 34 coaches. Even when they restarted services filling 3.4 coaches was a bit of a difficulty. Roadworks for the Silvertown Tunnel were going to make a bad situation at Blackweall worse, and TfL had a difficult relationship with the market - not treating them as local buses, even though they were, for example, or stringent requirements on layovers/parking. I believe there was also some redevelopment taking place at their daytime parking site. I was one of a few regulars who tried to persuade them to try a weekend service, but to no avail.