Disney/Hulu/ESPN count as one, though you can buy smaller packages.
ViacomCBS, NBCUniversal, WarnerMedia, and Disney will still be the big 4 of all the ones you listed. Amazon, Apple, and Netflix have minuscule content libraries by comparison. After people binge through new shows, the big 4 will be the ones holding all the old content. Netflix cant afford to produce content fast enough to backfill all their soon to expire licenses. Warner/Turner, Disney/ESPN, NBCSports also own a lot of sports coverage (CBS has a play as well) while Amazon, Apple, and Netflix barely have any coverage.
People are underestimating the play ViacomCBS will be able to make against NBCUniversal, WarnerMedia, and Disney now that they are united. CBS All Access and Pluto will be a killer combo, if they so choose to venture that route AND they own Philo to compete with Sling, Vue, ATT, Hulu, Youtube. CBSAA/Pluto/Philo is absolutely a threat to Disney/ESPN/Hulu's attempt at dominance; NBCUniversal(XfinityComcast), WarnerMedia(DirecTV/ATT/HBO whatever its named this week) wont go down with a fight either.
Discovery, Sinclair, AMC Networks all still exist as well. Verizon is making a bad play not gobbling up whats left.
At some point there will be a race to the bottom on price, and ad supported Pluto(CBS)/Hulu(Disney) like products will be dirt cheat to get people in the door. The extra money will come from people not wanting to watch ads.