In Kiswahili, "nataka" can mean "I want," but it can also mean "I am about to." Which is to say, it can express intention or desire, but it can also just mean that a thing (not intended or desired) is about to happen to me.
Does this double meaning exist in any other language?
Hm in English there's the colloquial "I'll take a sandwich" or "I'll have a sandwich" which both express "want/would like" in a predicative form. The French "je prends un …" is common too, and is literally "I'll take a …". All of these need the thing to be right there though, not a general desire.
In fact arguably both those English examples play upon "I will" — is it a prediction "I will do X", or an expression of desire "I will that Y occurs"? The latter is a bit archaic but hardly gone — consider last will and testament.
Presumably an entirely precise English prediction would be "I shall take a sandwich", removing the desire aspect. It sounds rather formal and a bit antiquated to me.
"Sollen" is great. Kelsen (Austrian legal theorist) used it initially to denote a legal "shall", and later expanded it to include a legal "ought to" and "is authorised to". Not everyone was convinced.
