Off-the-wall Jackson plans for invincible new release

A year ago, Michael Jackson said he wanted to get out of the music business after he had made his next album.

Many people assumed he had long since abandoned all ambitions to be a pop superstar, regarding him more as a superannuated weirdo, with his surgically induced waxwork-white skin, his chronic hypochondria and the gossip surrounding his relationships with young boys and his pet chimpanzee, Bubbles.

But now it seems the album is indeed coming, after multiple delays, and the big question is whether it will prove to be Jackson's glorious last stand or a monstrous white elephant that will sink what is left of his musical career in ignominy and reckless expenditure.

Invincible, as we are told the new album will be called, is due out on 25 September.

Industry gossip is already describing it as the most expensive album to be made, costing $30m (£21m) or more. Four years in the making, its 15 tracks have been whittled down from more than 50 recorded by a musical line-up of thousands and supervised by at least eight producers.

To say the album has had a troubled genesis might be an understatement. It was originally slated for release last autumn, then in the spring. Jackson's management company, The Firm, parted ways with him in frustration. The project was shrouded in such secrecy that even executives from the singer's record label, Epic, were not allowed to hear the fruits of their investment until just a few weeks ago.

Now a marketing blitz has been organised that smacks either of unlimited megalomania or commercial desperation. Jackson's entire back catalogue – Off The Wall (1979), Thriller (1983), Bad (1987) and Dangerous (1991) – will be released in remastered format in early September. A greatest hits album will follow. Then, in two gigs scheduled for Madison Square Garden in New York on 7 and 10 September, Jackson will introduce his new music in a lavish 30th anniversary tribute to himself.

To mark the dawning of his fourth decade in the biz, Jackson will appear with performers including 'N Sync, Whitney Houston, Ray Charles, Quincy Jones, Luther Vandross and Britney Spears. For good measure, there will be a 48-piece orchestra, 12 backing vocalists, a 300-strong gospel choir, a 200-member children's choir and 40 dancers.

The big question is whether any of this gargantuan effort will pay off. Thriller may have been the bestselling album of all time (51 million copies and rising), but Jackson's last release, largely a rehash of old material called Blood on the Dance Floor: History in the Mix (1997), shifted just 250,000 copies.

At 42, Jackson hardly has teen appeal, and it is not clear whether his older fans are still interested. Not only are they no longer breakdancing, but he is in less than perfect physical shape because of his well- publicised leg fracture at the end of last year.