The Android vs iOS graphs don't tell us a lot since Android is the accumulation of many devices across various brands, while iOS is just Apple's iPhone.
Dividing the share by brand or even by price point reveals the true competition in the market, Apple performs well in their category and regularly achieves the most sold smartphone. When figures were available these also revealed that Apple took home the majority of smartphone profits (90%+), that is unlikely to have changed significantly (Not because iPhone margins were particularly special, but because the market is saturated by competitors with razor thin margins.)
The Android v iOS graph is heavily skewed by low-cost devices. Apple's focus on a meaningful midrange product, long OS support and a build quality that is well above the low-cost alternatives are likely the reason why Android's share has declined by this small amount.
That said Apple won't achieve dominance in the bulk figures because these are buttressed by low cost devices, such as those used in less wealthy and developing countries. Can a large share of Android users even afford an iPhone?
This is all good for google, as users = profit, but it's not particularly inviting for smart phone manufacturers who don't have enough margin to develop a meaningfully differentiated product.