Somehow I don't think that the current light rail only plan will survive if transit taxes are implemented. It only made sense with a severe funding shortage. If a transit tax is implemented, voters will realize that building only light rail makes no sense if you have a much larger budget (say $30 billion). I would expect to see Rob Ford get his Sheppard subway (and Eglinton elevated) in exchange for full funding of the DRL.
We need something like this: <http://commons.wikimedia.org/wiki/File:Grand_paris_express.svg>. This subway expansion plan in Paris costs 30 billion euros, and the majority of it does not go "downtown". (The western extension of RER E is not shown on this map, and a number of additional tram lines are planned or under construction). This will reduce traffic congestion on congested Paris ring roads. Similarly, an Eglinton subway with a western extension to Pearson Airport/Square One, and a Sheppard subway with an extension to Pickering (running in median of 401 east of STC) would provide relief to the 401, and a Don Mills subway to Leslie/7 would relieve the DVP/404.