Don't get carried away. One DJ on one radio station mentioned one dot gTLD which he probably just read without thinking anyway. It's probably not going to be looked back upon as being the catalyst of the end of dot com.
We also don't know how many of the people that heard the announcement automatically without thinking entered dot com at the end of it when typing it into their browser or their phone.
I think that for the general public, "dot com" for websites is pretty deeply in-bedded in their subconscious and will take more than one radio mention to displace it, but that's just my opinion of course.