I wouldn't be surprised if that was planned, but honestly it seems that they'd have trouble working together in any sort of way seeing as they range in intelligence and lack a common language. I don't think they'd do an episode about them without them together in some way, which seems conceptually hard,
to me, Winona is the best mascot of all, she is courageos, helpful and loyal, well because is a dog, and also I like the dogs, they are so good pets =)
I can't help but wonder if Tiberius, Luna's pet possum in the comics, will find his way onto the show. Now that Luna's gotten a bit more characterization, it would be nice to see her connecting with the Mane Six through simple common interests like pets.