The reason for saying that English has no future tense goes beyond just morphology. 'Will' is a modal operator that has no inherent future sense. For example, you can say "John will be here already". You can't do that with a true future tense. See e.g. http://itre.cis.upenn.edu/~myl/languagelog/archives/005471.h... for more on this. If you try translating the examples at the bottom into a language with a true future tense, then 90% of them will come out as gibberish, or as meaning something quite different.