Yup its true, the developer, Sneck Tan has made it clear. Free service for ShoutMix is not a good business approach and sustainable. He has spent 7 years provide the ShoutMix for free and I have been using ShoutMix with my blog for couple of years, so I believe we must show our support to the developer to improve the service.
In his Open Letter, with the introduction of ShoutMix V3, a lot of his paid customer convert to free service. That is one of the main reason. He has no other choice.
By offering too much with our free plan, we cannibalized our paid plans. Happy users did not make more paying customers. The projections are bad. Only 0.07% users are customers. These are the people who keep ShoutMix sustainable as a business. Business is the part making ShoutMix exists for everyone. If it keeps on going this way, ShoutMix will not be sustainable any more and will need to close down in the near future.
So the free version is only valid for January 1st, 2012. After that it will stop working unless upgrade to paid plan. I just upgrade to Mini (Hobbyist Plan) cost me 99 cent per month. For me it still cheap and affordable. Plus, you can have 30 days trial. So 12usd per year is not that much.
Among key features are : Lightweight, Mobile friendly and Customizable.
But if you prefer FREE Shoutbox then I would suggest iShoutbox. Good Luck