No, it doesn't say it will replace injection molding. It says it combines it:
In theory, it could combine the flexibility of 3D printing with the speed and strength of old-school injection molding
FDM printing is very flexible since molds don't have to be made, but quite slow in the actual production due to slow speeds and layer by layer construction makes them not as strong. Injection molding is very inflexible due to molds having to be made, but once they are made, very fast in production and strong.
What this is, in theory is somewhere in between the two extremes. It prints much faster than FDM, but not as fast as injection molding. It's as flexible as loading a new file so almost anything is possible as quickly as you can design it without any expensive molds.
No, it's not going to be as fast as injection molding for creating a single tooth brush. But what if you wanted to custom mold a bunch with a dentist's name? Or maybe the technology expands and it can produce 100 or 1000 at a time so it expands better than injection molding. Or it's a very complex shape that's not conducive to injection molding.
A more real life example was my company wanted to make some flash drives in the shape of our product that has a distinctive wave on it. Quotes came back in the $3000 range just for the mold, and then individual costs of about a buck for the actual plastic. We needed about 250 of them. Even if it took a little longer and the cost was 10 more, we'd still be cheaper off with this type of a manufacturing technique.