Just my 2p.
BOM-MAN was one of 9W's weaker long haul flights (the other being MAA-CDG) compared to the AMS and LHR flights ex BOM. 9W could only make BOM-MAN work because of VS's strong presence at MAN and 9Ws strong presence at BOM - The flight funnelled many India-US two stop itineraries from Indian Tier II cities on a single PNR apart from serving a small O/D (presumably Indian VFR) market.
UK doesn't have that kind of network out of BOM now. I doubt they ever will go beyond serving only the current "top 10-15 city pairs" from BOM. Hence, If at all UK wanted to attempt MAN, they'd more likely do it from their hub in DEL.
Others have already posted why a UK-VS tie-up is not the most likely of scenarios, given that UK has a code-share relationship with BA.
But you need to remember it was only a few months old when Jet folded the newest routes are always the 'weakest', and when you consider the pedigree of cities Jet served Long Haul wise (LHR/CDG etc) of course it was going to be the 'weakest'.
I was replying in the context of your question, "why not MAN..?", and your statement "Jet has proved...".
Jet did not prove anything on BOM-MAN, IMO. They were merely attempting to make that city pair work because
they had support from VS (w.r.t onward US/NA traffic) to supplement India-UK O/D to fill their A332.
I believe that, simply because 9W attempted the route before they folded, doesn't mean that other airlines will now jump at the idea of flying BOM-MAN, even if we consider that the route was only a few months old.
In the case of AMS-BLR, o.t.o.h, I think the fact that KLM has decided to fly the route on their own metal suggests that Jet indeed proved the market existed.
I think those are some reasonable points made, if supported by the facts. However, the following points appear to have been omitted from your analysis:
I don’t think Jet opened BOM-MAN because of VS support. I’m sure it was part of the reasoning, but Jet had a number of European connecting points (LHR (for VS), AMS (for KL), and CDG (for AF). Obviously the P2P traffic between MAN-BOM has a relatively large impact on that - according to the anna.aero article below, MAN is the third highest European O&D market ex BOM (behind LHR and CDG). https://www.anna.aero/2017/04/12/manche ... -the-week/
I don’t think it’s right to say Jet haven’t proved anything. According to Routesonline (link below) before the route was operated the P2P market between MAN-BOM was 130,000 per annum. If you extrapolate the 4 complete months the route operated, the data suggests have substantiated a market of just under 130,000 per annum. Obviously this would have included some transfer passengers at either end (see further below) but there would still be a number of passengers opting for one stop routing. In summary, it is hard to argue that Jet did not prove the market for this route (in line with predictions). As this was at the outset of the route, it stands to reason that more growth would be possible once bedded in and once VS have started to implement their plans at MAN.https://www.routesonline.com/news/29/br ... bai-route/
Finally, I don’t think through traffic to the USA played a major role in the numbers established above. Jet operated BOM-MAN from November to mid-March, which is a period in which VS currently operates a relatively limited US network out of MAN (broadly speaking: JFK, ATL, MCO). I’m sure there was a decent amount, but the potential was certainly not fulfilled (also in light of the alternate options at LHR (via VS), AMS (via KL) and CDG (via AF). There is more to come here as VS expands it’s short and long haul network at MAN.
Having said that, I agree with your conclusion that airlines won’t be flocking to open the route. There are a reasonably narrow field who are based at either and and who could make it work. This is probably limited to VS at the MAN end, and Air India, Vistara, Spicejet and IndiGo at the BOM end. As noted, some of these might be more inclined to open MAN-DEL in the first instance. However, I suspect that within 1-2 years we will see this up and running again.