Wow! You made that very simple! But is it really? People say the Mini 2 doesn't scale well with iOS 9, and who knows if it will even support iOS 10.
And... is there really a mysterious Mini 5 in the offing? Considering that, Apple may retire Mini 2 and cut down the cost of Mini 4, which is good news for me.
Any thoughts on these?
Yep I'm serious with my answer.
About : 1. Online video streaming, you can do that on basically any iPad, it doesn't even require a powerful one so the mini 2 is good enough.
About : 2. Lotta browsing, well you can of course browse on the iPad mini 2 like any other iPad but the 1GB of RAM is really not enough to handle more than 2 tabs, you will get constant reloading and web browsing in general won't be as fluid and enjoyable as a 2GB of RAM iPad.
About : 3. Lotta gaming, the iPad mini 2 is still very powerful and won't have any trouble running any game you throw at it. Of course you won't have the beautiful graphics of a more recent iPad but you most likely won't notice a difference unless you have them running side by side.
Now about iOS, it is almost a hundred percent sure that it will run iOS 10. There is absolutely no reason for Apple to drop this device considering that the company is known for its legacy support and that the iPad mini 2 is only 2,5 years old (iPad 2 is 5 years old and still supported with the latest iOS version).
About iOS 9, I don't have an iPad mini 2 so I can't confirm you anything but from the reports and the few devices I have seen running this version, it's not as buttery smooth as it was on iOS 7 and iOS 8 but it will do the job.
And finally, about the iPad mini 5, we don't have a single information about it and seeing that Apple released an iPad mini 3 with the same specs as the iPad mini 2 (except for Touch ID) and that the iPad mini 4 launched in 2015 with an already one year old chip (the A8), I would not expect an iPad mini 5 this year. Apple seems to care less and less about the iPad mini lineup and focus more on the bigger iPads these days but who knows, they might surprise us like they often do.
Anyway, long post but I hope I helped you in making your purchase decision.