river sexy after turn check/check HU

[Lurker4]

I think this is a standard river checkraise but just wanted to check. Party 10/20 6m, currently 5-handed, folded to TAGish button who openraises. Button has TAG stats but has made some plays that IMO were suboptimal, whatever thats worth. I haven't been at the table very long and as far as I remember haven't gotten out of line. SB folds, I call in the BB with A[img]/images/graemlins/spade.gif[/img]2[img]/images/graemlins/spade.gif[/img]. Flop is Q[img]/images/graemlins/spade.gif[/img] 7[img]/images/graemlins/club.gif[/img] 2[img]/images/graemlins/diamond.gif[/img]. I check, Button bets, I raise, Button 3-bets, I call. Turn is K[img]/images/graemlins/spade.gif[/img]. I check, Button checks. River is A[img]/images/graemlins/diamond.gif[/img]. I check (obviously planning on raising). My question is, after Button 3-bets as drawless of a flop as there is and checks an overcard turn, does he nearly always have AJ/AT/Ax (which is definitely betting the river and likely calling a raise b/c my line looks weird). Can he have a pair like 88-33/J7-67 that just wants to pay 2.5 BB to showdown as opposed to 3 BB from calling my c/r and calling turn + river bets? Those hands don't bet the river but may call if I bet, even on this scary board. Another reason for betting is that since villain is a TAG he may (although its probably unlikely) raise the river w/just an A, so I'll get 2 bets in anyway vs Ax.