It's not impossible but an unlikely set of circumstances has to take place, namely:
1. Howard has to become Tory leader in 2001 after Hague resigns. He wasn't even a candidate in that election and he'd have to see off Clarke, Portillo and IDS - not the easiest of tasks. A Howard/Portillo pact would seal the deal as Portillo had scored a few hits on Brown as Shadow Chancellor between 1999/2001 but his university background would still scare many old-style Tories.
2. Howard has to shake off the "something of the night about him" image which Doris Karloff...er...Ann Widdecombe stuck to him in 1997.
3. After September 11th and Iraq, Howard should not roll over and be submissive as IDS was. However, extreme caution would have to be employed as the media will be all over the least bit of insensitivity or political capitalisation.
4. After Blunkett, Mandelson and to a lesser extent Millburn (and how the media didn't pick up he was shagging his secretary when it was an open secret in Whitehall) committed political suicide in the 2001-2005 term, more capitalisation could have been made of it all.
5. IDS packed the Shadow Cabinet full of semi-allies, he didn't actually have any allies. Howard would have to work harder to get the talented politicians in key positions and send them on the offensive.
I don't think Howard has the wherewithal to have done these things. 2005 was barely winnable for the Conservatives but it was winnable. Labour dropped the ball several times but IDS never picked it up and ran with it. He was an abysmal failure and if someone ever compiled the "10 worst leaders of the opposition" list, he'd rank number 1 as someone who just stunk.