There were many lingua francas of which French was supposedly the first global lingua franca. That changed and it became English (from what I understand). We will probably see another language become the lingua franca, so my question is: should it be English? Are there better candidates out there? Why / why not?
It’s a lingua franca, and I don’t even think it’s about being easy to learn… avalanche effects are completely sufficient to explain its status. Many people already speak English, so more people learn English to speak with them, now even more people speak English, and so on, and so forth… the development of any lingua franca only depends on the ability to talk to as many people as possible. It’s absolutely a bonus if it’s easy and quickens the process, but at some point the pure amount of speakers outside ones own country becomes the overwhelming factor.