Normally the OWE ticket use the rule when you purchase the ticket. (that's why old OWE still have 26 segments and all the stopover restriction when they re-issue at a later date when the new rules already up).

I think the same shall apply here, when you have your ticket, it said valid on AA/BA/CX........only or codeshare by another oneworld carrier (which as defined above, in the rule.

It may worth just to ask when LX is in and do a reissue but I don't think the new rule (with LX) should applies.