As Autoblog reported a few months ago, BMW is slotting upgraded, turbocharged four- and six-cylinder engines called the B48 and B58, respectively, into the 3 and 4 Series. If this happens, the 328i/428i would become the 330i/430i, and the 335i/435i would turn into the 340i/440i.
Obviously, this change hasn't happened yet, but the same member of 2Addicts, a portion of the larger Bimmerpost community has now claimed that the 228i and M235i would get the same treatment. They would become the 230i and M240i, respectively, with the new engines.
The exact source of this information isn't entirely clear. The user claimed to have access an inside source of future BMW model data. In one update to the thread, the person warned that the info isn't for certain but considered it "BMW's best laid plans."
The decision to alter model names with the introduction of new engines would seem to make at least some sense. We wish the numbers didn't seem plucked out of the air, though.