The BlackBerry software platform was even worse than the CE kernel based Windows Mobile, so I don't see how that would have helped them.
The problem was they didn't have a competitive software platform ready in time. In 2007 Google's Android team was already several years into developing Android and immediately started pivoting it into a touch based modern desktop class OS in a mobile package. Microsoft didn't realise that's what they needed to do until 2010 when they started work on Windows Mobile 10. But even in 2007 it was too late. They would still have been several years behind Android and there would not have been space for a sub-par licensed OS up against a free competitor that was years in front of it. The game was already over, it just took them 10 years to realise it.
The problem was they didn't have a competitive software platform ready in time. In 2007 Google's Android team was already several years into developing Android and immediately started pivoting it into a touch based modern desktop class OS in a mobile package. Microsoft didn't realise that's what they needed to do until 2010 when they started work on Windows Mobile 10. But even in 2007 it was too late. They would still have been several years behind Android and there would not have been space for a sub-par licensed OS up against a free competitor that was years in front of it. The game was already over, it just took them 10 years to realise it.