OData has supported two types of updates for a while now:
Now when we added MERGE there wasn't a standard HTTP way to request merge semantics.
However PATCH is now a standard, and is semantically equivalent to OData's MERGE.
So we think - given our principle of adopting HTTP and ATOM standards wherever possible - that the next version of OData should support both PATCH and MERGE, and treat PATCH requests like MERGE requests.