There are probably only 5 or 6 notable crunch time ISO scorers in the league right now: Durant, Carmelo, Lebron, Kobe... Wade?
Teams don't need an elite ISO scorer to handle their business in crunch time. They just need some great scoring plays they can turn to for reliable offense.
Wall is different than Rondo. Rondo used to become a crunch time liability because of his poor FT shooting. Wall is a solid FT shooter and his drive becomes a legit threat late in games with his ability to get to the rim against any D, finish through contact, dish, or get to the line and score. I think he needs to vary up his attack a little more and dish it more often because it seems like he tries to finish almost every single time now. But he'll master this eventually, often as he's trying it now.
And it's worth pointing out that Wall is showing a knack for making enormous clutch defensive plays. The block to secure the win in Denver and the strip steal and fastbreak layup come to mind. That's just within the last four games.
Beal has also shown signs of being able to score in crunch time against strong D, beat double teams and hit big shots late. He's got a versatile inside--out game that's going to be effective in 4th quarters.
I don't think we'll have access to any true star players this year. The only one who seems likely to go on the block is Dwight and that's obviously not the crunch time scorer you're talking about. Pau and Amare will probably be available too but nobody wants them. Cousins is a potential star and probably unavailable. Gay is not a star.
I want to see how the lottery shakes down. I'd probably keep the pick and use it if we end up top 3 or 4. The only guys I'd really want to trade for are Cousins or Dwight if he'd do a sign and trade long term extension.