Battery replacement scheme was available India. But, due to absence of Apple store, users have to go to Apple authorized service vendors where services take days. It took me 5 days to replace the battery in Dec 2018 because battery had to be specially ordered.(I live in major Indian city.) Cheap Android phones from Xiaomi etc are flooding the Indian market. If Apple doesn't ramp up the quality of experience in areas other than Hardware and OS, it's gonna lose whatever market share it has in India.

That’s India’s fault for not allowing foreign companies to own stores:

https://www.quora.com/Why-is-there-no-Apple-store-in-India-1

I can’t imagine Apple headquarters wanting to ignore a 100 million rich people market, but obviously it’s not worth the trade off of having to become business partners with someone they don’t want to be partners with.

Well Samsung, One Plus and others are thriving in India, they dont have their own stores. So clearly its not the stores. The major factor is price (Apple tax + Indian Tax = One very expensive phone.

My understanding is that the only thing that really matters in China is the availability of WeChat.

What phone you've got matters little as a result. So Apple doesn't enjoy its usual iOS-stickiness factor.

That's not quite right, although yes WeChat rules in China. Having the new shiny does matter - source, my wife is Chinese and I have a Chinese sister-in-law and niece both which got the X last year.

They are absolutely typical Chinese consumers in this regard. As soon as iPhone because hard to distinguish from other phones they switched away. As soon as iPhones became clearly distinguishable again they switched back. This is not just an observation, they say this is why they did it.

I think there are actually three factors hitting Apple in China this year. One is that a disproportionate number of purchasers got the X when it came out because it was so distinctive bringing forward purchases from this year, then there are a lot of Android phones now that look like the X models and the new X models don't look enough different from the original X to look new, finally the economy in China is pretty soft right now and people there are worried about the future.

You missed the fourth, which is a trade war going on that is inducing a soft boycott of iPhones. Some of those users may be lost permanently to local alternatives.

WhatsApp has pretty much eclipsed iMessage in many markets too.