What i mentioned only sits in Cat31 (voluntary changes) of the fare rules which are only supposed to be used for automated reissue which is not used everythere so far and not even available for all markets.
So it does not mean the airlines enforce it in practice. On the other hand when I tried to change my one RGN ticket after first component used at BKK DL office the system did not want to follow the rules which I had in the fare, and recalculated all 'as of today'.
Actually my feeling mostly went out of SU rules, i seem to have seen same in DL rules but only see classic 'using fares when ticket was issued' now. So maybe false alarm.
Randomy checked UA, LX, KL - OK, historic prices after departure (moreover, the rules do not say anything of no show...).
Cat 31 not found: LH, AZ, KE, TG.
Hopefully what SU is now doing is illegal (Russian law applies for SU tickets):
OR -
AFTER DEPARTURE OF JOURNEY AND WITHIN TICKET VALIDITY
CERTAIN DOMESTIC REISSUE PROVISIONS MAY BE OVERRIDDEN
BY THOSE OF SU INTERNATIONAL FARES
NO CHARGE CHARGE HIGHEST FEE OF ALL CHANGED FARE
COMPONENTS AND
REPRICE USING FARES IN EFFECT WHEN TKT WAS ISSUED
PROVIDED ALL OF THE FOLLOWING CONDITIONS ARE MET-
1. NO CHANGE TO 1ST FARE COMPONENT
2. WHEN NO INTL COUPONS REMAIN - ALL NEW TRAVEL
MUST BE DOMESTIC
3. FULLY FLOWN FARE NOT REPRICED TO FURTHER POINT
4. SU FARES ARE USED
5. ALL RULE AND BOOKING CODE PROVISIONS ARE MET
6. ADV RES IS MEASURED FROM ORIGINAL TKT DATE TO
DEPARTURE OF JOURNEY