The biggest challenge with these kind of migrations is training users, especially government employees. Switzerland is relatively highly educated so this might be less of a challenge than in other countries but it won't be easy.
The technical part is probably relatively easy in comparison. Especially because the stakes are low (parallel run with the existing system, good will from everyone involved).
The technical part is probably relatively easy in comparison. Especially because the stakes are low (parallel run with the existing system, good will from everyone involved).