I think it's too early to tell.
That said, the Wii is selling faster than the PS2 at this point in its life, and successful consoles tend to sell better and better over the course of their lifetimes (look at the PS2 sales).
I would have to wager that it is indeed possible, and I would bet that yes, the Wii can surpass the PS2's worldwide lifetime sales.
PS3: 5.51m/51w, avg 108,039/w (up 239)
360: 12.93m/102w, avg 126,764/w (up 625), leads PS3 by 7.42m (up 70k), avg lead 18,725/w (up 386)
Wii: 13.52m/51w, avg 265,098/w (dn 1,102), leads PS3 by 8.01m (up 90k), avg lead 157,059/w (dn 1,341)
If 360 sales stabilize, PS3 sales increases needed to pass 360 by...
01/08: (008w) +875.8%, 04/08: (021w) +344.4%, 07/08: (034w) +219.3%, 10/08: (047w) +163.5%
01/09: (060w) +131.8%, 04/09: (073w) +111.4%, 07/09: (085w) +098.1%, 10/09: (099w) +086.7%
If Wii sales stabilize, PS3 sales increases needed to pass Wii by...
01/08: (008w) +1072.%, 04/08: (021w) +498.4%, 07/08: (034w) +363.4%, 10/08: (047w) +303.1%
01/09: (060w) +269.0%, 04/09: (073w) +246.9%, 07/09: (085w) +232.6%, 10/09: (099w) +220.3%
If PS2 sales freeze, Wii sales increases needed to pass PS2 (as of Mar07, 108.4m) by...
2008: (008w) +4373.8%, 2009: (060w) +0496.5%, 2010: (112w) +0219.6%, 2011: (165w) +0116.9%
2012: (217w) +0064.9%, 2013: (269w) +0033.1%, 2014: (321w) +0011.5%, 2015: (376w) -0004.8%
At +0% it will pass it in 358w, the week ending September 19th, 2014, at an age of 409w (7y44w).
Current age of PS2: 7y37w.
Last update: Week ending November 3, 2007
