Matt,
What you say is true, IF (a very big IF) things progress like people think they will. Unfortunately, as volatile as this industry can be, high oil prices, another viral epidemic like SARS or H1N1, or a terrorism scare, or if someone farts while standing on the wrong foot can cause a cascading effect of cuts, downgrades and furloughs.
That being said, yes, if you choose wisely and have luck on your side, you COULD progress quickly in the next few years. Regional airlines are hiring at a steady pace right now, and it seems like there is finally starting to be movement at the mainline level. With some luck, it will hold out and pick up steam over the next few years. I wouldn't count on fast progression and certainly choosing a carrier simply because you think they will allow for a quick rise through the ranks is far from the wise way to go about it. There are no guarantees in this business, today's cherry gig can easily become tomorrow's bottom feeder. Creating a timeline will likely only frustrate you so try not to give yourself so many years to get to a certain point.
The bottom line is it comes down to you, and what you want. If you want to fly, and have the support of your family, pursue it. It will be very tough, and require a lot of sacrifice from you and especially your loved ones. If anything, fly on the side and finish your commercial and move on to other ratings while keeping your finger on the pulse of the airlines. Watch trends and watch the forums and sort through the b.s. and rumors and look for fact. We have a lot of very intelligent posters on here who offer great insight into what is going on with certain companies and sectors of aviation. If, as you progress, you find that flying is just something you absolutely have to do then have a come to jeebus with your family and get their input. If they're behind you and you want to do it, go for it.
Keep in mind today's left seaters at the regional level aren't about to get a windfall. They've spent years at their respective carriers and for the most part have several thousand TPIC and have watched 9/11, Age 65 and various other downturns stick them at the regional level longer than I think any of them wanted to ever be there. They've earned their shot to move on.