Yeah I worked with errea for years. I actually took Les Motherby over there and they showed him the proposal they had done for City a couple of years back.
At this time of year errea will have most of their Pro clubs kits in their warehouse and on their way to the clubs for launch, but they work pretty different to other brands in terms of lead time. They stick to their guns no matter who it is so would not even consider trying to produce something for City in a matter of weeks.
Someone like Nike or Adidas could do it, Castore the same. They would be able to get a factory to make a bespoke kit in serious numbers within 4 or 5 weeks. You can get bespoke with Adidas but they just wont do it for small numbers.
If City have designs they may well stick with them for another manufacturer, designs are not copyrighted.
The way I see it there are probably 3 options. They stick with Oxen as they're way down the manufacturing process and it will cost too much to pull out, depsite the money potentiall being offered. You would think if it was being done properly some merchandise is already in production. Sponsors will be the key, if they were holding out for a main shirt sponsor knowing it would double or triple the income in the Premeir League then the shirts wont be in production.
Or they switch brands and potentially delay the launch of the jerseys/merch until July. This would allow them to bring in a proper brand who is offering serious loot. An extra 2/3 Million would be impossible to turn down, even if it means paying someone off a few hundred grand for wasted initial stock.
Third is that Acun sticks with Kappa as he has the licence and realises the income potential of manufacturing your own shirts in the numbers we are likely to see worldwide. Unlikely as he doesnt seem to have the right people managing this for him judging by the state of the merchandise and retail offerings since we went with Kappa.