It is also interesting to note that the Chinese Samyukta Agama (SA) has been reconstructed by Ven. Yinshun and in this reconstruction the Khandha Samyutta is first. Personally I think the structure of Pali SN is a bit jumbled. And the structure originally could have well been similar to the reconstructed SA.
In this topic you can find the reconstructed SA:
The Chinese Saṃyukta Āgama (SĀ) presents a unique challenge to producing an English translation. The version of the collection that was preserved in the Taisho Daizokyo is in disarray. The collection lacked any divisions or sutra numbers, so it apparently came to pass after it was translated that its fascicles were shuffled, and a couple were lost. The two lost fascicles were replaced by some helpful soul with Avadāna translations by Guṇabhadra to make 50 again. The text then fell into obscurity…