Not sure they officially abandoned the 49,000 years of creation idea, they just stopped talking about it.
That's a common WT Society tactic - Franz mentions it in one of his books that a GB member ( Schroeder , I think ) if the Society just stop talking about something then the "brothers" soon forget about it. It must be even easier nowadays that the religion is so dumbed down.
Even the 7,000 year long last creative day , which we assume is still a Society teaching , is looking a bit shaky now and getting even more farcical by the minute. According to "WT bible chronology" (lol) , the first 6,000 years ended in 1975 ( hence the famous" Armageddon is nigh , sell your house" etc nonsense of the late 60's / early 70's ) so already over 45 years of the last 1000 "millennial" reign has gone. This also means Adam was alone for at least 45 years. No wonder he was pleased to see Eve!