...what they usually do: work hard on creating (and improving) an awesome product. Peldi always seemed to focus on the product more than on the competition.

myBalsamiq is being developed by a proven team and they have quite some headway in terms of traction and features (in particular the project management features, it's more than a sketch app). Does this mean they will be the only ones making money in that market? No. There's always room for a different take on mockups, but it's going to be tough to compete directly with Balsamiq.