I noticed a lot of mocks here are still using the old 90's era chart for valuing draft picks. There is a an updated chart that Sando from espn wrote about a few days ago http://espn.go.com/blog/nfcwest/post/_/id/95011/about-that-old-nfl-draft-pick-value-chart
Why does this matter to the 49ers mock drafts? The FO is one of the league leaders in modern FO analytics usage. This means they value first rounders less than teams using the old chart (which is almost completely arbitrary, btw) and value 2nd and 3rd rounders much, much more. If you want your mock w/trades to be more accurate, you should probably trade our 1st down to pick up more picks and you should probably not trade away our 2nd or 3rds.
You never know whats going to happen since its all probability based, however currently there is a trade arbitrage between the teams on the old charts and the teams using the new charts. I expect the FO to continue to take advantage of this arbitrage and pick up more picks, rather than funnel them into a few high picks.