I'm more surprised that Musée de l'Air et de l'Espace, the current owner of MSN4, has given Airbus permission to modify a museum piece.
Airbus gave them the frame and are presumably also assisting in getting it ready for public access.
I'm sure it's not going to be that hard to come to an agreement about attaching some for-show-only winglets (as has now been confirmed in the FG article posted by A330freak) to that museum piece.
Wow no retrofit? This A380plus is officially a dud to me, I don't see how this is going to garner new orders from existing operators or gain new customers.
Well, they want to attract customers to new-built A380s, as they're struggling to keep production rates up. In that regard, they need to be sure CASM is competitive with the 777X. It's basically a cheap A380neo they're doing in an attempt to keep the plane attractive enought to be able to wait out the market picking up until a full-blown A380neo makes sense. Hence their focus on new-builts. That is obviously a bit of a gamble, but the resources required for this are not going to break the bank, and it's not even formally launched yet, it's just a study (maybe a study that came out of initial studies for the A380neo). Once they get interest for 20 A380plus or so, the whole enterprise will have been paid for already.
With regard to retrofits, remember that when Airbus launched sharklets for the A320 in 2010, they initially did so only for new-builts, with deliveries from late 2012. They only launched the retrofit programme in 2013, with deliveries from 2015. It's quite conceivable the same thing could happen for some of the A380plus improvements.