kebab shops on busy streets near bars could be a growth area.
Definitely not. The market was way over-saturated ten years ago, and since then, a lot more kebab shops have closed than have opened. A lot of pizza joints have added kebab to their menus, which greatly increases competition and reduces demand for dedicated kebab stands. There are precious few, if any, virgin markets that are not already served by existing players in the market.
Of all the businesses to get into, gastronomy is hellish even in the best of circumstances. Expect the worst to happen, and you will not be disappointed.