There's no doubt that sport (particularly football and cricket) are a sure way to quickly gain market share in certain countries. The problem is, this fact is very well understood in the industry, and therefore the content rights are priced accordingly. I'm in the UK, where it costs a
lot of money to acquire Premier League rights, and I doubt it's exactly cheap anywhere in the world.
The question for Netflix — and any content distributor — is whether the benefits justify the price. This calculation will be different for every organisation, based on their financial resources, expansion plans, existing market share, customer base, target customer base, etc. I suspect that, at the moment, the potential benefits from expanding into sport aren't justified for Netflix. They have a strong brand based on access to high-quality, episodic "TV-style" content, that is driving good growth already. Moving into showing live sports would be an expensive risk.
I suspect we'll see Netflix expand into streaming live events eventually, but probably not mainstream sports and news to begin with. It makes more sense for them to identify emerging sectors, such as esports, which have the potential for strong growth, but for which the rights are still relatively cheap.