That was my plan 
I had a look into the usage of housenumber=*. It is used 306x at the moment. About half of these objects seem to be added by a single user. These look a lot like typos for addr:housenumber=*. I contacted the user in the changeset discussion. There is no object, where housenumber=* and addr:housenumber=* store the same value.
Another 80x housenumber=* is used in combination with tags of emergency=* for some kind of fire hydrant or water tank. As this combination is used by several users in different places (all in Russia) I wonder if theses where intended uses. Does anyone know anything about this? The examples I checked where creaed by accounts that have only a few edits and that are inactive for a long time now.
Most of the uses of housenumber=* are probably typos for addr:housenumber=*. Some of them may also be addr:housename=* or ref. I think that this can be included into one MapRoulette-Challenge with the remaining street=*.
postcode=* is undocumented and used exactly 7x spread around the globe. As the number is so low that can be included into the MapRoulette-Challenge.