It's going to vary massively by the content deals that they have in place for each country but after a long enough period, all the deals with expire and Disney will be the only place for Disney content. (Legally anyway).
If I was Sky, I would be crapping myself. This idea is now getting floated about as well:
Disney+ makes Sky Movies almost pointless and that Premier League idea makes Sky Sports redundant for most.
I think Comcast bought Sky but I'm not sure if it went through or not.