Hey there,
first of all I would like to compliment you guys on the great work done with NEM. I just got into it, and I really like the concepts behind it! I appreciate how easy to use it is so far.
I have a question / suggestion in mind that bugs me for some days now, so I thought to share it here. Maybe someone might help me out on that 
I am a developer and I have a use-case in mind which I would like to try out NEM for, specifically (but not only) the Mosaics feature in order to issue a token based on the NEM blockchain technology. As far as I understand, Mosaics can be used as a currency for custom “side”-applications communicating thru the provided API with the public blockchain. Users of the “side”-application would have to hold the Mosaic to use the services and in order to transfer the Mosaics also hold XEM.
This approach makes a lot of sense to me, since harvesters need to get paid somehow to include transactions into the blockchain, but is also impractical for providers of services on top of the NEM technology.
So, here comes my question: Is it planned in the (near) future to adapt this model to make transactions payable thru the provided Mosaic? I know this could be complicated since a Mosaic doesn’t necessarily have a value attached to it, whereas XEM does. Alternatively, would it be possible that a different account pays the fees, when someone else spends the Mosaics? This could make it easier for users of Mosaics to spend these directly (without holding additional XEM) by still supporting the NEM network thru the Mosaic provider.
I apologize in advance for anything stupid or incorrect I might have said, but that’s how far my understanding of NEM goes at this point. I hope this topic is worth discussing about 
Greetings