OneWeb has a real, real problem now. They are burning cash, not making any money, and are not anywhere close to commercial service.

Moving to a different launch vehicle right now is horrible for them because quite simply there are not any, with exception of maybe SpaceX. That would directly fund your competitor who is already beating you.

The reason is that because of what SpaceX achieved around 2014-2015 the launch industry is moving into its next generation. However right now we are in a transition phase.

Lets go threw all rockets of any size.

- Russia Proton -> Destroyed commercially by SpaceX, unreliable, production has ended.

- Ariane 5 -> Destroyed commercially by SpaceX, sold out, production ended

- ULA Delta 4/Delta 4 Heavy -> Destroyed in government by SpaceX, sold out, production ended

- ULA Atlas 5 -> Sold out to Amazon and production ended.

- ULA Vulcan -> Not flown, engine delayed, flights booked for the next couple years at least even if it flies this year (unlikely). However, overall maybe the most likely as they actually have production capacity for the rocket itself at least. The engines are a different question.

- Japan H3 -> Delayed, booked for years, low launch rate

- Relativity Space Terran R -> NET 2025 at best (and then low launch rate for the early years)

- Rocket Lab Neutron -> NET 2025 at best (and then low launch rate for the early years)

- New Glenn -> NET mid-2023 and given engine production, real commercial launches at real, who knows. New Glenn is very low launch rate and reliant on them perfecting re-usability immediately.

- Ariane 6 -> ESA/Europe need to shift their own Soyuz launches to Ariane 6, likely no commercial availability for many years.

- India GSLV Mark III -> Very, very low launch rate and fully booked years in advanced for Indian missions.

I have less information about China but I have heard that LM5 is also basically done and they generally have a lot of their own launches. Unlikely a British/Indian rocket would use China.

SpaceX Falcon 9 of course also has a huge number of flight, likely more then all the above combined. But its at least possible that they would sell you a real block of launches that would allow you to finish your constellation in the somewhere in 2023-2024.

Around 2027 there will be lots of very large rockets looking for payloads to hope to manage their flight rates. But right now, you are out of luck.

Some people on Twitter suggest launchers like Astra, RocketLab, Firefly and so on. This is likely not commercially viable. Launching these sats 1-4 at a time would likely be way to expensive. Not to mention that it would basically overload the small launch market far more then it could handle.

So, OneWeb went bankrupt once. Now they are backed by gigantic governments and quasi-government in Britain and India. They better hope those people don't know about the Sunk-Cost fallacy.

OneWeb only real advantage was being first to market. Technologically both Starlink and Project Kuiper are on a totally different level already.

And I don't think OneWeb was doing massive R&D to compete in the tech race during their hard time. It hard enough to get production going for their current sats.