It seems like conventional wisdom right now is that the 49ers must trade up, as there is a good chance that the 1st round talent for WR and CB will be chosen before they pick at #30. However, trading up requires a partner, and there is no guarantee that the 49ers will have a good option for trading up. So if they end up staying at 30, they have the option of taking BPA at an area that is not a need, or trading the pick. They don't really need more picks, so they could afford to possibly trade #30 for a first round pick next year (which also depends on finding a trade partner), and then draft for players that they need with the other 5 top 100 picks that they possess.
So what would you do at #30 if there was not a good option available at CB/WR?
1. Overdraft the next best CB/WR
2. Draft BPA
3. Draft BPA or take a next year 1st round pick if offered
4. Trade down to acquire additional picks in this year's draft