I have worked with e-commerce related companies so I can offer some perspective here.

The battle in india is far from settled, it is important to look category wise. Moreover in context e-commerce one should not ignore alibaba backed paytm which seems to be working on a super app strategy and big basket which is into grocery.

Website visits- Amazon seems to be ahead. From Jeff's shareholder letter - "Amazon.in is the fastest growing marketplace in India, and the most visited site on both desktop and mobile, according to comScore and SimilarWeb. The Amazon.in mobile shopping app was also the most downloaded shopping app in India in 2017, according to App Annie. " This does not include numbers for Flipkart owned myntra I think adding that might take Flipkart ahead since myntra is the biggest in fashion. Moreover play store might not give a complete picture since many devices come pre-installed with apps in India, my phone had Amazon app pre-installed which will not count towards play store download.

Mobiles - This currently the biggest category in e-commerce. Accounting for 60-70% of sales. Here they are neck to neck but it is hard to make out clearly since e-commerce is heavily driven by exclusives and brands like Lenovo and Xiaomi are playing them against each other.

Fashion - Myntra owned by Flipkart is ahead here. Amazon is catching up but is challenging to match a vertical player in user experience.

Electronics - I don't think there is a clear leader here. Due to logistical challenges for major brands it is still convenient to buy offline apart from some sales period when discounts can be really high in e-commerce. Of late though lot of offline stores are ready to match the ecom players, I saw this while buying TV plus they had faster delivery and installation. This might play out like mobiles with lot of Chinese brands who don't have offline networks competing on pricing and using e-commerce for distribution.

Grocery - Amazon has a lead over Flipkart. It has multiple plays like Amazon now, Pantry etc. Flipkart is piloting a model similar to now in bangalore. The competition comes here from alibaba backed big basket which also has perishables and in my personal experience provides better service vs Amazon. Walmart might give a boost to flipkart here with its expertise in grocery. However unit economics are worst in this category. High weight low average selling price means shipping cost eat up a lot of revenue.

Video - Amazon has more users than Netflix. The challengers here are Jio with it huge base, cheap data and good library and hotstar with its biggest strength being Indian TV shows and live cricket and football. This is extremely nascent in India so every network has their own app but these two + Netflix seem the most likely to be around for long. Netflixs pricing in India is pretty high so will be mostly used by the affluent sections and not mass.

This deal was unusually public. I think Amazon was never seriously into it. The valuation is insane plus Amazon would have run into some antitrust issue plus this being an election year in India, government might act tough against such acquisition. The good thing with Walmart is that there might be more sanity in the market since it is a listed company and can't just burn VC money.