Pffft.... Those discussions about phasing out and buying aircraft are so stupendous. If I read the posts correctly, there are at least 6 magazines, each claiming different things about KLM widebody renewal.
To put things on order:
1: KLM has never ordered A340's, not even signed a LOI...
2: KLM never searched the market for 2nd hand MD11's...
3: IF the MD11's leave, some of them are intended to stay in the company, probably with Martinair as a freigter.
4: KLM orders planes with payload in mind, not range. And since both the 777 and A340 don't cut it for them, MTOW-wise, they'll probably go for 747-400's.
(747-400Combi has the same amount of seats as a MD11)
I won't dare guessing what they'll get in 200-300seat range... Nobody can tell, and knowing KLM, they will never tell anybody until they finally order. Face it: Nobody saw the 737-800 and -900 order coming. They are very good at keeping their orders a secret.