Nah, not really. despite Gold not being quite the series' equivalent to Fire Emblem Awakening that some of us were hoping for (Though it's way too late for that IMO), I think WarioWare in the long run will be fine.
It managed to outsold G&W in Japan, made the charts in Europe (Even if it's at #40) and while it's not doing great in NA, it is arguably doing better here then a lot of smaller 3DS games, sure it's not exactly great and I would have like to see better, but Gold doesn't seem to be doing outright horribly or what not, at worst, we'll probably get another 5 year hiatus or what not, but I doubt the series would just outright die or whatever.
Even if the sales fail to impress Nintendo (Hopefully they don't have high expectations.), that could be blamed less on the franchise itself and more on the 3DS' current state as a lot of people have since moved on, or are moving from the system in favor of the new and fancier Nintendo Switch. (Well, that and the terrible and almost non existent marketing.)
Overall, I'm not too terribly concerned about the future of the franchise at the current moment.