Anyway, regardless of all the terminology involved (or should that be potentially "involved" terminology?!), the main thing that we are concerned with really is the power of the mind and imagination in making sense of the world through what it knows already, through processes of comparison, analogy, metaphor, whatever. Let's not get too hung up on being precise - not that we've been that precise so far! - we can all just go read the literature!
It doesn't really matter what you call it, the only thing that matters is the allusion to something already known (or that could be quickly and easily taught to a student who didn't even know the basic meaning to begin with, let alone have any conception of extended meanings/uses).
As as example, I was talking to a Japanese guy yesterday, and used "I bet..." (with its "surmising" function, based on what somebody has told me up to now e.g. this guy recently did a breakneck tour of Hokkaido and Tohoku in a weekend, and only had a few hours sleep on the way back to work on the Monday, so I said, "I bet you were tired at work!").
He didn't "get" the "bet" first time round, doubtless because he didn't know or expect that it could be used in conversations away from the racetrack or schoolyard ("I bet you ($1 that you) can't...!")*, but he did know (thankfully!) the sense of "bet" in sports/gambling, and the idea of YOUR OPINIONS CAN BE (LIKE) MONEY, TO BET IN A CONVERSATION was very clear and intuitively appealing to him. Furthermore, the action involved in leaning forward excitedly to "bet" with your "money" (versus the more "detached" alternatives he offered, such as think, suppose etc) also made the "feel" and distinctiveness of the word (that is, its use here) that much more apparent. "Bet" seems to involve more "risk" than detached language, so it can bring people closer together (that is, more is being "invested" in the conversation, which will probably make the people feel more "valued"

).
From that, he could readily understand the meaning of phrases like: You bet!, You want to bet?!, I wouldn't bet on it etc - the person mentioned is(n't) going to stake "money" on something (being true or not)!
I don't know if this use of "bet" is metaphorical, or figurative, or whatever, and such distinctions would be too academic for learners; all that mattered was reminding the student of "known" things, and extending the meaning slightly by processes of analogy.
Teachers have been using analogy long before the metaphor "movement" came along, but mainly just in a purely "semantic" sense/way (i.e. "The meaning (use?) of this word/structure is almost/very/quite/somewhat/a bit etc similar to that other word or structure that you already know"); all we are doing now is trying to focus on how people conceptualize the world (rather than argue the toss about meaning based on "outside" authorities - but obviously, corpora are blurring the line between what we think people might say (detached or potential meanings of the language - competence) and what they do actually say (instantiated meanings)).
The fact that both me and the student could see and agree that the "two" meanings of bet were closely related shows how powerful and useful cognitive processes in action can be.
* By the way, I felt like pointing out to him that "...tired at work" (regardless of "betting!" vs question intonation - not that I mentioned intonation, or questions vs "invitations" etc to him specifically!) was what carried a lot of, if not most of the meaning in what I said (i.e. I had made a "proposition" about his tiredness at work), and that he therefore shouldn't've totally stopped conversing to worry about what "bet" meant; but as he had reasonable English generally, I guessed that he "knew" TIRED, AT and WORK, and therefore presumed that he had had no "problem" with "tired at work" specifically (even though he hadn't responded to what I'd said), so it didn't seem a crime to forget the conversation and study "bet" instead. That is, it's hard to insist on top-down approaches to listening comprehension if students don't go for it, if they still feel that there are some words they simply "have to" know to "fully" understand! Maybe we just have to accept that these "temporary" lulls in "conversational competence" will correct themselves naturally later (when the student not only HAS learnt, but FEELS they have learnt enough to be able to confidently tackle "top-down" approaches to comprehension).