Tenses are not distinguished by their semantics, but by their grammatical form. That is, the same tense (in this case, future simple) can be used with different semantics in different contexts.
You could argue that the "sometimes" has actually become codified into a part of the tense (so the verb phrase is not "will have" but "will have sometimes") and then it could be considered a new tense. But someone would have to analyze this language use quite carefully to see whether it has become codified in this way, or if it's just about using the regular future simple tense in a slightly different sense or in a somewhat formulaic manner.
> Tenses are not distinguished by their semantics, but by their grammatical form.
Annoyingly, people don’t always keep these two definitions as separate as they should be. This means there are language-specific grammatical structures called ‘past’/‘present’/‘future’, and also idealised temporal semantics called ‘past’/‘present’/‘future’. This is why you get things like the so-called ‘English future tense’, which is used sometimes as a future tense but just as often for modal certainty.
(The situation is even worse when it comes to aspect. It took me a very long time to understand what ‘perfective’ meant, because the ‘perfective’ category in different languages means different things!)
You could argue that the "sometimes" has actually become codified into a part of the tense (so the verb phrase is not "will have" but "will have sometimes") and then it could be considered a new tense. But someone would have to analyze this language use quite carefully to see whether it has become codified in this way, or if it's just about using the regular future simple tense in a slightly different sense or in a somewhat formulaic manner.