Sure, French was itself something of a lingua franca in centuries past, and Spanish is already a great candidate because it has, right now, more native speakers than English. I learned Spanish in school as a third language just because (we had to choose between Spanish, French and Latin) - didn’t stick, though, listening comprehension for Spanish is very hard and there wasn’t enough incentive for me.

English’s hegemony as a lingua franca is to a very large degree because of the US, especially after the UK lost almost all of their colonies after WW2. That said, English would probably still be a minor lingua franca in northern Europe, because it’s a lot easier to learn than a romance language if your native language is germanic.