How long do you think I could keep using my iPhone 5S before apple discontinues updates and other services on it?

I think after this phone I'll go to a iPhone 6 or to a android phone that performs the same or better than the iPhone. I was really disappointed when they removed the headphone jack and drastically changed the outside design of the phone so there's no possibility of me wanting a iPhone 7 or 8. I've been using iPhones for 4 years now and using apple products for 7 years so i'll really miss the iPhone when that happens. And I've had my 5S for 2 years now

If Apple keeps according to its current update cycle the 5s should get updates until September 2018 (before iOS 12).

As indicated by the latest Google Pixel phones removing their headphone jacks, its just a matter of time where even more remove theirs as well (others also have already)

As far as the external design, some have criticised Apple for not changing the design basically among the 6, 6s, 7 & 8. The X of course is the most drastic change in iPhone design since 2014.