As I understand the issue, all that's been discontinued by Oracle is MySQL's db2 for IBM i storage engine. This storage engine allows MySQL applications to access db2. If support for this storage engine is not restored by Oracle, then as Kent said, perhaps another organization could pick up the slack. (That said, I'm not going to rush into heavy use of the storage engine till this issue is resolved.)
MySQL itself can run on the IBM i even without the db2 storage engine. I recall that in 2004 or 2005, before there was any official support for MySQL on IBM i, developers were compiling MySQL from source code so that it could run on the IBM i (i5 at that time). In fact, one of our IBM i servers is still running an old MySQL binary created in that prehistoric time.
Therefore, I have confidence in the IBM i's ability to run standard MySQL-based applications, such as WordPress, now and in the future.
If Kent or anyone else can find a flaw in this reasoning, please add your comments. This is an important issue for the community.