So with Sponge you can create plugins just like Bukkit just with a new API. You can also create plugins with Forge mods in mind as well like mcMMO supporting the trees from Biomes O Plenty. I heard somewhere here about with the Sponge API you don’t need to update your plugins or its very easy to and its not hard. Sponge being an API that dosn’t change much between Minecraft updates. Unlike Forge you can’t do that. If you can update your plugin that adds mcMMO compatibility with Biomes O Plenty and its still in 1.8 but 1.9 Sponge is out and you want to add compatibility with the latest versions of ExtraBiomesXL (for example) it being in 1.9. There would be a problem. Would you have to wait for them to update their mod before you can update your mcMMO compatibility with a 1.9 version of ExtraBiomesXL wood.What will have to happen? Could you update it and still have it compatible with an older version of MC?
ALL MODS AND PLUGINS IN THIS ARE EXAMPLES. PLEASE UNDERSTAND!
Walls of text and run-on sentences are a delight to read. (facepalm)
If your plugin is designed with mods in mind (read as you’re aware that mods may and may not be introduced at any point in time), then there won’t be any problems.
SpongeAPI itself will NEVER add API specific for any mods as those mods may come and go (let alone take time to update).
You can easily rely on soft compatibility if for example certain BlockTypes and ItemTypes aren’t available (you’d have to check) but as usual, between MC updates (and mod updates) those compatibility layers may have to change based on various circumstances (like from Thaumcraft 4 to 5, lots of things changed).
Try to be helpful next time instead of pointing out grammatical issues in someone’s post.