If the rumours were true that Comco was going to prohibit ETA from selling to third parties, that's a completely illogical decision. As ETA has noted, Sellita is now the dominant player in the market, and driving ETA out of that market makes no sense, particularly in the context of the paragraph below - it isn't explained in any detail, but it's important to this story:
"In 2016, Swatch Group asked to supplement the agreement. The supply quantity agreed upon had not been purchased by third-party customers but ETA was obliged to maintain a production capacity of around 1.5 million movements. Therefore, Swatch Group requested from COMCO that ETA should be allowed to offer and sell the non-purchased quantities to all of its third-party customers – which was rejected."
In the original decisions and agreements that allowed ETA to stop being forced to supply third parties, Comco mandated that ETA had to keep making movements in specific numbers to keep the market supplied through the duration of the settlement. The thing is, the number of movements they were required to make far exceeded market demand, partly because other brands started producing their movements far quicker than Comco anticipated. This left ETA holding massive surplus movements, so that is why they wanted to sell off those movements, but Comco refused. Now if they are telling ETA that after 2020 they won't be able to sell them at all to third parties, that will leave massive inventories of movements sitting unsold in warehouses, and on ETA's books.
Comco is making a mess out of this...