I just can't see the Cards going with a guy who can't block at all as their #1 TE. And Dray as #2 in an offense that is supposedly going to feature two TE's. What does Dray do on special teams that makes him so valuable?
As for Lenon how much of a market is there for 35/36 year old ILB's when it is such an easy position to fill with younger guys?
There are lots of teams that have good offenses and feature tight ends who can't (or refuse to) block in the #1 role: New England did it for half the year when Gronk went out, Green Bay, New Orleans, the Giants, the Eagles, Minnesota, Houston, etc. There's no reason that the Cards can't have a successful offense with Housler as the primary TE and another guy out there who puts a little more effort into blocking.
If Dray is going to be an in-line blocker, he can be fine. He can also be a fine outlet receiver. He's an excellent player as a blocker on kick returns and in the punt and kick return game. He's a valuable player.
Contra Chopper above, there's nothing special personnel-wise that the 2TE offense provides--there's no real tactical advantage. There's a
strategic advantage, because when you have at least one tight end adept at both blocking and receiving (such as Gronk or Jason Witten or Heath Miller), you force many opposing defenses to commit to defending the run or the pass by the personnel they deploy--a 3rd linebacker vs. a 5th defensive back. A quarterback can then easily audible to a run or a pass that immediately presents personnel mismatches.
I'm going to argue that getting a 2nd TE on the field will usually come at the expense of getting a superior option off the field, either Andre Roberts or Michael Floyd. That's especially true if you're talking about a rookie tight end. If Arians and Moore are going to preach that they're going to tailor their system to the personnel available, they'll be running an offense primarily with 11 personnel for the 4 games or fewer that Ryan Williams is going to be healthy but ineffective and 20 the approximately 8 games where Beanie Wells will be healthy and effective.
Running a 12 personnel base offense is explicitly sacrificing quality personnel for what you believe conforms to your "system." If they do, it will be quite telling.
As for Lenon, I don't doubt that he would come back; I just have some doubt that the Cards would really want him back, since he was the closest defensive player to Ray Horton, who was summarily run out of town in order to establish a clear chain of command.