After reflection, and also checking books and web sites, I now think that "will" should be used, because the tense of the preceding verb (is
being taught) is the simple present. Thus the supposed future event (failure of the taught methods) must be expressed in the simple future (will).
If the tense of the verb had been the simple past (was
being taught), then the supposed future event would be described using the "future in the past", (would)
Simple present verb, therefore "simple future" event:
What is being taught will probably not work.
She says she will visit us next week.
They know that we will be arriving tomorrow.
Simple past verb, therefore "future in the past" event:
What was being taught would probably not work.
She said she would visit us the following week.
They knew that we would be arriving the next day.
This is not to say that the distinction is always observed in everyday use. However, it is better to know the rule, then you can decide how important it is!