Is ESPN+ a standalone streaming service?

Yes, ESPN+ is available as a standalone subscription or as part of the Disney Bundle. It is not a replacement for ESPN on cable — it carries content not available on the linear ESPN channel, including UFC Fight Nights, college sports, NHL, MLB, international soccer (LaLiga, Bundesliga, Serie A), plus exclusive 30 for 30 documentaries. ESPN on cable carries NFL and NBA which are not on ESPN+, so the two are complementary rather than identical.