"When one thing is practiced & pursued, ignorance is abandoned, clear knowing arises, the conceit 'I am' is abandoned, latent tendencies are uprooted, fetters are abandoned. Which one thing? Mindfulness immersed in the body." -AN 1.230
"to beings who have come to be and those about to come to be." Metta Sutta
I understand bhuta va sambhavesi va differently.
Bhuta: Those who have become
Sambhavesi: Those who are arahants or anagamins. Compare thasaa va thaavaraa va.
Note: The name Metta Sutta is not unique. It is called Karaniya metta sutta by some. It is one of the Suttas in the Sutta Nipata. The Sutta was a kammatthana for bhikkhus at the time Lord Buddha. The 14 qualities necessary to practice this kammatthana is given in the sutta beginning with: sakko... It is not possible to translate these suttas to English or to any other human language.
However, a word by word commentary is possible which takes the context fully into account,