They traded 3 picks spread over 3 years....and yes 2 of them were 1st rounders (though likely to be in the 20's) PFF actually estimated the value of what the Lions got in picks as the equivalent of 1 Top Ten pick.
As of now the Rams have their 2nd round pick in the next 3 Drafts
They still have two 3rd's this year (assuming a comp pick) and next year they have 2 Thirds (Their own and for Holmes) and could ultimately have 4 Third round picks (with comp picks for Johnson and Floyd)
If the Rams end up with Six 3rd round picks in two drafts, Snead will almost certainly make moves with some of those picks to produce additional picks or players.
So they'll have plenty of picks in Rounds 2-4 in the next 3 years,where Snead has really shined. Snead also frequently trades down to get more picks during drafts.
The only thing that could hurt the Rams depth is if they start missing on a lot of those 2nd-4th rounders. They are going to have plenty of chances to get quality players....more picks than most teams will have.
The reality is, what they gave up to the Lions will have little effect on their depth over the next few years.
And they got a QB that could get them in another Super Bowl