By Lars Mucklejohn The consolidation of mid-sized challenger banks will likely ramp up in 2024 and more lenders will start winding down, the chief executive of digital bank Cashplus has told City A.M., as the market becomes increasingly crowded. Rich Wagner added that legacy banks are experiencing a “brain drain” as their digital-only rivals poach top talent. Wagner is in his 20th year as chief executive of Cashplus, which launched in 2005 and secured a full banking licence in 2021, mainly serving microbusinesses and smaller SMEs. “20 years ago, when I started this business, there were nine ma…