It's unfortunate, because it would have been good to keep as many guys competing for the spots after Edelman/Hogan for as long as possible, to assure you made the most informed decision on who to keep. But as was pointed out, WR was always going to be a numbers game, with 7 vets competing for 5 spots (assuming none of the rookies/2nd year guys step up). Now it's 6 competing for 5 spots.
The question during the first 4 weeks isn't necessarily which WR will replace Edelman, but how will the team choose to run the offense in his absence, and there's different personnel options to do that. When you have a TE like Gronk and RB's that excel at catching the ball, you really only need four WR's (three to play regularly, one for depth). Hogan and Dorsett seem to be having good camps, so I consider them 1/2 until Edelman returns. I think Patterson makes it, but he's a #4 at best (gadget guy who can play in high WR sets and be an ace on ST).
#3 Wr options look like this (in order of my personal preference):
1) Mitchell gets healthy. He's the guy who has proven he has Brady's trust and gets it when he's on the field. Big question mark right now, but all things being equal, he'd be the best guy.
2) Britt take the next step, which reports have indicated the team is optimistic on.
3) One of the young guys steps up and earns a slot role, allowing Hogan and Dorsett to man the outside spots. I haven't heard much about any one of them really standing out above the others yet though.
4) Until Edelman comes back, we keep an extra TE or RB and run a lot of 12 and 22 sets for the first 4 weeks. I think this can work in the short term, but even once Julian is back it speaks to paper thin depth at WR.
Lots to watch in the coming weeks.