It's currently at about 70k and by launch could do near 100k.  Obviously it's at the end of PS3's lifecycle but still should get good buzz as previews have looked promising.  I'm planning on buying it (not at launch but BF should be good) and I think it'll do around 1.2m lifetime.

The previous Sly games have gone like this

Sly 1: 1.2m

Sly 2:1.8m

Sly 3: .8m

Sly collection (not digital obviously): .5m

It will eventually sell more than 1 million, I think It can actually reach 2M ltd. These kind of games on PS even though they dont usually have a good start, they have "good" legs.

Wait... it's out?!

No, not yet.

I think considering there haven't been many releases in a while it will either help or hinder its sales. I'll guess about .6-1 million.

I really hope this game does really well. I love the original three Sly. I'm very surprise they decide to make this game this late in the PS3 life span.

Can't see it making the million mark, in my youth at least..

I see it selling just shy of 1m but maybe vita sales (if they count in this question) pushing over the 1m mark. I personally plan on buying this only for my vita because i've never played a Sly game so only paying $40 is reasonable to see if I like the series, plus i need to save memory on my vita memory card for playstation plus games.

I think it was series fatigue at that point, they were released back to back and IMHO 3 just wasnt as good as 2

I can only speak for myself here. I bought the first game and adored it, one of the best games on the PS2.  I was all hyped up and then the second one came out...  

Instead of the tight brilliant level design you had open world which was just meh.  Also while the first had a few annoying bits it made up for it with so much good. I spent much more time just getting through 2 to find something enjoyable.

By the time 3 rolled around it looked like more of 2 and I just ignored it. I did buy the HD collection just for 1 and found it aged great while the others did little for me. Have a wait and see on 4 to see if it goes back to original or continues the decline.

Agreed, the whole open world element ruined Sly 2 and 3 for me. I don't mind a hub base, but having the entire game set in a large city just doesn't make much sense to me. I think the series works better with tight level design. If Sly 4 works more like the first game then I'll definitely pick it up.