I am mainly in sports apps. I think it is still possible to have succes. It requires a lot of patience. Don't focus on the revenue part. And don't try to build a new hype. Very slim chance you build the next angry birds. Instead try to build a product that is based on an already successful specific category/ product. Very important is that you understand your customer and genuinely try to make a product that is better than the competition. You should love your own product. The good thing is that bigger companies tend to destroy their own product with too many ads, notifications, non relevant features etc. Furthermore I believe it's important that your product contents can be automated without too much manual work. After all you are the only person with only so much time. I know a guy who created a fitness diet app. He cooked and photographed more than a thousand meals. He wrote many articles. In the end he gave up. It took him 80 hours per week to maintain and update all the content. His app was making maybe 100 a month. I know another guy who created a successful formula 1 live app. He is using paid data feeds and scrapes a lot of additional data. Everything automated. Spends like 10 hours a week maintaining things. Makes about 100k a month. Similar story for a guy who created a popular weather app. In essence the only thing what they do is aggregation of data and present it in a relatively simple app. Also don't spend too much time on analytics, seo and other optimizations. It may take 2 years before you get traction anyway. First the product then after (if it's worth) the optimization. One concrete product where I think you can still have success is a baby monitor with 2 phones. Couple of good apps only. All premium priced. Not too difficult technically. I don't have time for it, so go for it :)

great advise, thanks for sharing!