assuming that there is no such agreement between kde and digia, the code is already GPL for win/linux/mac/andoid. everyone can get the f***ing code and copy/fork/redistribute it
Open source developers are not concerned by that fu**ing commercial version anyway.
the agreement grants kde an extra-exclusive right to relicense Qt under the BSD
if Digia drops GPL'ed Qt, the code is here and the community can continue developing it for all platforms.