What I find disturbing about things like Replika is all your conversations are owned and stored by the company. At least with a real-life partner, there's not a database that someone can query to pull your intimate in-person discussions.
Can you imagine creating an emotional space for something {subject to Microsoft's TOS and updated unilaterally}?
In addition to the drifting line with intimacy... suddenly you have a privileged position with a huge userbase.
How long until people's agents start recommending {product of the week} in conversations?
That said: as the tech progresses, it wouldn't surprise me if the line between human-human friendships, and human-AI friendships blurs over time.
People are wired for connecting with other beings, but friendships come in many forms. Wouldn't rule out AI-based somethings filling some of those roles.