Ok. Lets look at it a different way. You are a new company. When You release this product and you sell it for X$. People buy it but not enough to keep your new company alive. Then a year later your company goes under and all the people who bought the plug in cant there models converted.
Or lets look at it another way. You are only selling people half a product. You will make people dependent on your company in order to get there models coverted to the right format for your plugin. Later you want to make it a subscription for your service and then it becomes a recuring cost to your clent base. Eather one of these sanaroios are not exseptible. Do the right thing and relese the entire product. Companys releases service packs all the time and it is not a big deal and cpu power is faster then ever before.
Not to be argumentitive but people should not buy software that is only half the product or that they have to keep paying for.
Like I siad in my first post. I think you have a great product but you need to make it standalone with all the bells and whistles on the client. Not on a server in your data center.