The Sven Co-op team announced with their 4.8 release that it would probably be the final version of their mod. The reason for this has now been made clear. The team have not stopped development, they have in fact brokered a deal with Valve to release a stand alone version of Sven Co-op. The team have been given access to the GoldSrc engine code by Valve and will be making their own version of the engine to provide a better co-op experience, including expanding the limitations to allow for larger and more detailed maps. The game, when ready, will be released for free to all Steam users. No purchase of is Half-Life required, not even to play through the Half-Life campaign which will be included with the release. The team is also working on improvements to the Hammer level editor. There is no mention of any sort of release date or ETA but you can check out the the official announcement over at the Sven Co-op site.