We've consistently highlighted amiibo stock issues as a failing on Nintendo's part, in actually producing enough stock, communicating clearly and managing expectations or - perhaps most accurately - a mix of those factors. Stock shortages have also led to some inaccurate assumptions about discontinued figures, too, and Nintendo's merely stated that it's working on providing stock while admitting that, yes, not all figures will be renewed forever.
That's been the company line for a number of months, in defence of the big N, even if the news that some figures will be limited runs is not what we want to hear. The ambiguity over which figures are limited isn't ideal, but it is increasingly looking like Little Mac will be one toy that'll be hard to procure. The rumour's been about for a short while, but an accumulation of circumstances seems to suggest that the little challenger may be on the ropes.
An article on geekparty.com highlights attempts to get hold of a Little Mac amiibo, and following the removal of the toy from GameStop's website at the end of 2014 (triggering initial rumours) the following answer was given when enquiring on stock.
We deeply apologise however Little Mac Amiibo was delisted / discontinued. Since we will no longer be receiving any stock of this item due to manufacturer shortages/cancellation we would be unable to fulfill [sic] your request
A look around retailers such as Amazon and Best Buy in the US returns a lack of stock or inflated marketplace prices; it's a similar case with Amazon and GAME in the UK. Little Mac isn't the only amiibo currently out of stock at most outlets, of course, but the circumstances are piling up to suggest that it may, indeed, have been discontinued.
We'll reach out to Nintendo and share any response we receive.