To be fair..that's the impression Nintendo have been putting out there.
They said no Zelda..and they have said multiple times that they'll be showing games launching in the near future in the event, emphasising it'll be to show 2015 releases and some early 2016 ones (which is why Zelda won't be shown as it's not due in that time period).
Nintendo's statements have pretty much told fans to manage their expectations as we already know what almost all of their 2015 games will be (on Wii U at least).
Has this actually been said, or are we drawing this assumption based on that Zelda delay tweet? Because I always felt people took that too literally overall. Due to the retailer invitation thing that leaked, we know that 2016 games will be there, and I don't recall there ever being any kind of specification that it will be only early 2016 titles.
I mean, like I said, I'm not saying we're in for some blowout show for sure. I, like everyone else, won't know until a few hours. But it is interesting to me how the assumption is already pretty dire.