Would they still be in power now?
Maybe, maybe not. If they are, and got a majority or two, the next election would be see them back in opposition. Otherwise, Kenney or whoever succeeded Harper would be champing at the bit for the chance to chuck the (most likely Liberal) government out.
I think that Martin taking the reigns of government only to immediately lose it would discredit his camp. So I imagine those standing for the leadership would be Chrétien loyalists and cabinet ministers... which is not a bad bench to pull from. Possibly contenders would be Allan Rock(1), Frank McKenna(2), Brian Tobin(3), Martin Cauchon(4) and John Manley(5)... maybe even Dion(6) too, though I don't think he could win here.
1. He'd be great for a Liberal Party that was expecting to spend multiple terms in opposition. But he was a shitty justice minister and he'd be a terrible PM.
2. Probably wouldn't be bad either as leader or as PM. A Blue Liberal who be able to pull votes away from the Tories. His main drawback is that no premier has ever held the equivalent federal office.
3. Has the drawbacks of McKenna but lacks the ability to pull votes away from the Tories. Would probably be a good caretaker, but wouldn't win the election.
4. Too closely connected to and thus would be pounded by AdScam. He'd be a walking, talking election ad from both the Bloc and the Tories.
5. The best of the lot, one of the 'Best Prime Ministers we never had'. A respected Blue Liberal who could win Canada wide.
6. Look at his OTL performance for how he'd perform TTL.
Though I do have to agree that Martin is toast. Going from being 'the guy who'll win 200 seats' to 'loser' in six months would see him out on his ass immediately.
Chretien's faction of the Liberal Party would have to contend with a government eagerly bashing them with AdScam at every opportunity. The Tories would be all for letting Gomery finish his inquiry, and would likely call for a criminal investigation of those involved in the affair. This may or may not lead to charges, and certainly would still be in the news whenever the next election is called. And it wouldn't just be Tories attacks that would need to be fended off: Both of the other opposition parties would be quite enthusiastic in their own attacks on the recently dethroned Liberals, as they'd both stand to benefit greatly.
Also, the politics of the last decade would be interesting, even more so than they were OTL. Just look at the last two years that Martin held power, and think of what happened. What was enacted into law? What wasn't? And how much of that would be switched were Harper the one running the show instead? IMO we'd be better off, but other may think differently.