Hi Chris, thanks for reading through the post. I do agree that messaging platforms have all the three characteristics you have mentioned and are essential for a good user experience.
And that is why I believe mobile-browser in itself can be a messaging platform. Why make a user switch from a browser to a messaging app when the same(or even better) experience can be delivered right where he has discovered your services/business.
Browser in itself is an unconquered territory and we at Tars see a huge opportunity here.
Would love to know what you think.