Is the idiom in the offing used and understood now? It is present in many lists of English idioms, but I have never encountered it in real life. However, if one makes a search on Google News, one will find out that this idiom is used in Indian news-sites that write in English. For some reason, it is more popular in India.
It's used in the US, but primarily when imitating a British accent, e.g. in the A C Doyle takeoff, Sherlock Holmes and the Whitechapel Vampire by Dean Turnbloom.
Yes, it's used. A quick Google News search gives plenty of examples outside the Indian press. For example, the following headlines:
"Bush-Clinton sequel may be in the offing for 2016" (Detroit Daily News, 24 December, 2014)
"Bigger home loan package in the offing" (Bangkok Post, 18th December, 2014)
"Board shake-up in the offing at Covered California?" (Sacramento Bee, 17 December, 2014)
"Don Cayo: Official letters confirm major tax increases in the offing for hundreds of businesses" (Vancouver Sun, 16 December 2014)
The article "MBE honour is ‘wonderful’, says Sheffield cinema leader" (Sheffield Telegraph, 1 January, 2015) leads with "A visit to Buckingham Palace is in the offing for Sheffield cinema leader Dr Stephen Perrin..."
Since it's used fairly often by the press, I assume it's fairly well understood by the readers.