Here's the thing: Slack already won. Slack won before you were even on the scene. Slack has won so thouroughly that it's winning converts from IRC, which is largely the hardcore crowd, and is somewhat outside of Slack's target market (team chat).
Bashing Slack isn't going to win you much in the way of customers, because all it tells them is that you want to be Slack. They already know that. Everyone on the playing field wants to be Slack, except IRC, which mostly doesn't care. Instead, show your customers all the ways Slack is better. Ask them if Slack has your awesome new feature that will increase their productivity tenfold.
If you want to kill the leader in the field, you have to give us a reason you're better. And "they're so last year" isn't a reason, unless you're a fashion product.
When I read "Slack is so last year", my first thought was "Oh, so Ryver is just this year's Slack." That's not a win, because I already have Slack and I don't need this year's trendy new version. That ad might have a high click-through rate, but you need something better than click-through to sell an enterprise client.
Pitching new features would be more appealing, but you have to actually have new features that are good. Task management is nice, but there are lots of Slack-integrable options already going.
As is, I'm really not sure what this pitch is supposed to say: "our well-established competitor is well-established"? Sounds good to me.
Yeah. If there's one well-established option that works well, why would I convert? As it stands, there are up to 3 well-established options, depending on your domain: Slack, XMPP, and IRC.
Maybe you are right that the game is over and Slack won. I don't think so. I believe they uncovered a market not even they knew was there. If I am correct there will be quite a few winners in what I believe to be a huge market. Over the next decade EVERYONE will gradually stop using email for their team communication. That is 1 Billion business users of email.
When I took SalesLogix public in 1999 there were other CRM companies that went public around the same time. Multiple winners. And where I am going with differentiation ultimately I don't care what Slack does. I only care now in order to become a known brand. Something we have pretty good start on.
Bashing Slack isn't going to win you much in the way of customers, because all it tells them is that you want to be Slack. They already know that. Everyone on the playing field wants to be Slack, except IRC, which mostly doesn't care. Instead, show your customers all the ways Slack is better. Ask them if Slack has your awesome new feature that will increase their productivity tenfold.
If you want to kill the leader in the field, you have to give us a reason you're better. And "they're so last year" isn't a reason, unless you're a fashion product.