Compliment and maybe out-number? Possibly, yes.
I don't know about outnumber. When one considers the vast number of personal PC's, netbooks, laptops and servers out there both in the home and in the workplace........I believe it would take a long time to even come close to having the same number.
As to the question itself in general. That's like asking if iPad's (I still say that sounds like a feminine hygiene product.......lol) will replace PC's.
There's so much more you can do on a PC than you can do on a phone or pad.....period end of story. I suppose for some folks, the smartphone may be all they'll ever need but for the rest of us, we'll always want our PC's.
For me personally, no phone or pad will ever replace my PC's. Heck, I just had my work cell replaced a year ago and they tried to foist a smart phone on me. I refused. I asked for, and got, a cell phone that has:
a) a good, strong battery
b) gets excellent signal strength
If I don't use my cell the battery can go over 7 days between charging.
When all the smartphone crowd can't get a signal, I'm still showing 3 out of 4 bars of signal strength.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.