They have even less incentive to do anything now, because they can just tell their customers to use Tesla's superior, reliable network.
No one is buying Tesla's because of the "quality of electrons" that get put into their car. It's not like superchargers are some advertising opportunity for Tesla. When I go to Tesco and use the VW sponsored free PodPoint chargers there, I'm not thinking "mmm this makes me want to buy an ID.3" (and those ones even have video advertising).
Tesla's Supercharger network was the motivator for legacy brands to work on improving their offerings/public offerings.
I am also not at all convinced that the revenue from charging non-Teslas will make up for the loss of vehicle sales in situations where the network was the deciding factor, or that whatever revenue they do get will or can be channeled back into more sites.
Tesla will lose Model S sales to Porsche for sure now, and Model 3/Y to other marques - guaranteed.
I think opening up the network is a terrible idea. Great for TSLA shareholders I guess, but pretty crap for existing owners who are losing a USP and consequently some residual value in their cars. Although I don't personally need to use superchargers, I'd be lying if I wasn't concerned about a depreciation shock on my car when this becomes a thing over here.