The DS put up a good fight but it looks like the PS2 is going to remain on it's thrown for the most sold console/handheld. Looking at shipped sales the DS shipped 151.52 million as of March 31st, 2012. Now I'm not sure of the to date numbers of the PS2 but as of November 21st, 2011 the PS2 shipped 154.4 million consoles, so it's safe to safe including holiday boost the PS2 is over 155 million by now, but let's use this number for calculating. So that makes the gap about 3.5 million away shipped. Nintendo also forcast that the DS will ship about 250K for next quarter (which is about what it's selling 21K a week).
Now a look at weekly sales shows that the PS2 and DS are probably pretty even. The DS is averaging about 20K a week, now it wouldn't surprise me if the PS2 was close to that number, it had a very strong hold inthe East over all consoles and in Japan there about the same. According to VG chartz actual sales are 153.68 million for the PS2 and 151.82 for the DS, thats about 1.8 million away for consoles sold.
Now let's say the DS is selling 50K more then the PS2 every week (way overestimate yes, but should even out for holiday sales) then it should take the DS 70 weeks to outsell the PS2 (almost fall of 2013), now that's if the PS2 stops being shipped today and the DS average 50K every week for the next 70 weeks...not looking good.