This was going to be my other point, also. I can see that the cheap(er) J/F fares we've been enjoying on EK will either go, or will remain, but only on EK codes (QF codes more).
I really struggle to see what EK is really getting out of this, the cons seem to outweigh the pros IMHO.
For EK, all I can hope is that the QF influx will push up load factors (on both airlines would be nice). Not sure how many EK customers will appreciate more links to the Australian domestic market, but QF were obviously hoping that would form some component of benefit (both to EK and QF - the former for connections, the latter for load factors). EK also has a truck load more connectivity options on Trans-Tasman (admittedly the quality of services offered by QF is not up to the same standard).
EK has had problems with getting more slots into Europe, where they want to attack with more flights. Being "forced" to by hopefully more traffic through QF's customer base (no matter what shape or form that takes) may give them more impetus so that they can aggressively get more flights (or more aircraft). As a last ditch effort, perhaps EK can help support QF to apply for slots into Europe that cannot be obtained by EK (the Germans in particular are not too happy giving any more traffic to EK, and LH know that well. EK has also had troubles with Canada and further traffic there, which AC has also been staving off with its lobbying.)
Hopefully they will eventually draft an agreement where each FFP's members can earn points
and status irrespective of whoever markets the ticket.
That said, as alluded to by
JohnK, the problems will be consistency of earn. For example, Class Bonus is currently at 50%/100% extra for J/F on QF (marketed) services only (not BA and AA); going on the same trend suggests that EK would also "miss" on this Class Bonus and use the more default 25%/50%. Status Bonus is currently only earned on QF, JQ, BA and AA services; once again, a guess may suggest that EK services would miss out on Status Bonus, unless they are "close" enough to QF in this agreement to be included in that subset of airlines.
As for Economy classes that will earn at the 1.00 rate, QF will more than likely maintain the current trend of all Economy classes earning 1.00. With EK marketed tickets it may be different. I'd like to see at least 0.50 for cheapest Economy (vs. 0.25 for BA Y), and
all classes earning something (viz. would be sad if the cheapest Economy fares, e.g. sales, do not earn anything if marketed with EK). The dilemma would be not much different to QF codeshare vs. marketed on AA or BA Economy, where often the earn rate would be 0.25 - 0.50 rather than 1.00, which would only be earned on full Economy fares.
Status credit earn (except for the overarching issue of QFFers earning them on EK marketed tickets) will otherwise be consistent, though if there are ever double or bonus SC promos, these usually work on QF marketed tickets only, so naturally there is a "minor issue" there.