Going out on the limb of a sequoia.
I think Whitehead could be gone because there are PR/KR/offense players who are better than him. Streets is gone and I think TWilly will be reduced. The way that Whitehead made the team last year and that Brice Butler was traded for, seems to point to a need for change.
Here's what I think is going to happen:
Ed Eagan
1. There are certain qualities that succeed in the NFL right now: Odell-Beckham is not that fast nor tall or strong, he can catch anything because of handsize. Dez gets all kinds of accolades about his "talent" but aside from being very strong and violent when he runs, his catching radius is really based on his 9.75" hands. I tested this theory last year when Stefan Diggs was a prospect and I had hoped Dallas would draft him. Diggs is like 5'11" (they have him listed at 6' but that was not what he was listed in college) or big and his speed is like 4.43 so he is decent (the average starting CB in the league is 4.45). But Diggs has 10" hands and if you watched the Minnesota games, the Norv offense gets covered fairly easily so Diggs had to make contested catches (and Bridgewater is not that accurate), but Diggs outplayed Mike Wallace, Corderelle Patterson, and most of the NFC just by quick feet and ripping the ball out of the air. Eagan's hands are 9.37"
2, Laurent Robinson and Miles Austin were the last two WRs with significant roles on the team who could get open just with their speed. Robinson is still ranked 6th all time in his 10 yard split and Austin reportedly had a 40 time of 4.24 at a Rutger pro day (he ran a 4.38 at main pro day). Beasley doesnt get the prominent role for some reason and Dooley said last year that he "wants to expand Beasleys route tree" so despite him being fast and quick, they don't want him to have the distance routes (and the offense is almost all distance routes except Witten and RB checkdowns). My guess with Beasley is that Romo can't see him. This offense is not set up for Romo, Romo has adapted to the offense (that's why Garrett tries for tall WRs over those who can catch). But anyway, Eagan's short area quickness and his vertical speed is closer to Austin and Robinson than Beasley and because he can rip the ball out of the air (and has a 34" vert), Eagan has a better shot on the outside as a #2WR than Beasley would.
3. Amendola. We all knew Amendola could play and that Dallas should have kept him. But he was somehow not approved by Garrett's offense. Most of the fans thought he would be (and have) the shifty, former soccer player uncoverable WR that Welker was. Maybe he was not quite that but he was productive. I remember Jason saying something about "well we wanted to keep him..." once someone asked why Dallas would give up a WR who was starting for the Rams. Last year, it was obvious again that Dallas needs a speed WR who can play KR/PR and adds speed to the offense. So last year it was obvious that Whitehead was the only candidate. But Whitehead is not really a polished route runner and he is not great with pure catching. If Eagan and Whitehead go head to head, Eagan is going to win.
4. Need vs Depth. Its weird because they added TEs after having Escobar, Hanna, Witten, Swaim and now Gathers and they signed Austin Traylor as a UFSD but despite not being pleased with TWilly and Streets and Brice Butler still being a questionmark (after all he was not even playing really for the Raiders except in preseason games and yet "Dallas as high hopes for him"...wrong), they did nothing to upgrade WR. They have Morris, Dunbar, Rod Smith, and DMC and they drafted EE plus Darius Action Jackson. Many draft "experts" cited WR as a need because of how TWilly disappeared (and he is in his contract year) and how Streets is doing nothing. But no WR was drafted and only Eagan, North, Chris Brown and Andy Jones were signed after the draft. North, Brown, and Jones all play the same style of tall and lanky. Eagan is different. I heard on the Dallas radio station that "Jason just thinks he can put anyone into his system and doesn't need to get specific talent" and if that is the case then Eagan has a good chance. I am not sure they are sold on Whitehead anyway. It seems he was kind of a second thought on most games. I think Jerry might be a little bitter on how well Dwayne Harris is doing in NY, when Jason would not use him as a WR that often. But Garrett talks a lot about versatile athletes and Eagan, against lower level opposition, is a strong KR/PR and special teams player. But he also caught 73 passes last year in an offense that is 56-44 run/pass ratio. Just kind of makes it happen. Like Beasley did.
5. Run after the catch and Twitch. Eagan runs kind of like Edelman but is quicker in traffics than Whitehead. He seems to have a great sense of where the tackle is coming and avoids it. He can increase his speed in a chase like Dwayne Harris and not get caught from behind like Murray or Whitehead did.
I know this is odd saying all this about a player who has not played anything (and may not) and I knew nothing about the player until I watched the highlights, but Dallas has a gap in the pass offense between Witten's consistency, Dez's power and Beasley's reliability, and to me it's missing a player with rugged quickness like a Welker or a Randall Cobb (whose height, weight, 40 time and handsize are identical to Eagan).
Okay. Tee off.