The problem with the auto industry is that you can't tell that improvements are being made until the new products reach production, which can take years. All of GMs new products are doing relatively well, G6, HHR, cobalt, LaCrosse are doing as well or better than their predecessors. I'm confident the t900s will own what's left of the large SUV market, and the pickups will probably steal some share as well. The current SUVs are where most of the incentive dollars are, so once the new ones are out, GMs total incentive spending should plummet (so they'll stop most of the bleeding).
GM just needs to get rid of the rest of their 'dogs'. Namely the Grand Prix, it needs a complete redesign yesterday. I've already mentioned the old trucks. I'm not 100% the new impala and monte can hold their weight beyond a year or two. I don't think they have enough visual appeal to stand out in the market. Hopefully they'll be moved to a RWD platform by the end of the decade, and the redesigned (and supposedly very hot) new malibu can pick up the slack for chevy. The new crossovers will be huge i feel, and saturns new lineup will be a winner. So, i think if GM can hold out for 2006 limping along on the current product, the big introductions in the next two years should bring them back.