A post to a thread called "With baited breath, I say" on the DropShip Command Forums by FASA Studios' "Von" paints an uncertain picture of the future of the MechWarrior franchise, indicating that for the moment they have decided to discontinue plans for MechWarrior 5, but they do plan to "re-invent" the franchise. Here's the significant portion:

Over the past few months there has been plenty of speculation, email, and pleas for information regarding the future of the PC MechWarrior franchise, namely MechWarrior 5. Although an exceptional effort was made by an extremely creative and talented development team, we have decided not to continue the development of the project at this time. There were several factors in this decision, but most prevalent was our concern that we were not advancing the genre enough to meet and exceed our customer's expectations. Please know that this was a very difficult decision, but one we felt was in the best interests of our customers.

We deeply love the Mechwarrior franchise, and are committed to keeping it alive. Our plan is to re-invent Mechwarrior in a way that brings a fresh experience to our devoted customers and new fans alike. We would like to thank all of you for your continued support of the Mechwarrior 4 series of games, and greatly appreciate all the feedback we've received on our games. We are intensely focused on delivering outstanding game experiences, and rest assured we are working feverishly on some wonderful next-generation games.