"Monks, I will teach you the All. Listen & pay close attention. I will speak."
"As you say, lord," the monks responded.
The Blessed One said, "What is the All? Simply the eye & forms, ear & sounds, nose & aromas, tongue & flavors, body & tactile sensations, intellect & ideas. This, monks, is called the All.  Anyone who would say, 'Repudiating this All, I will describe another,' if questioned on what exactly might be the grounds for his statement, would be unable to explain, and furthermore, would be put to grief. Why? Because it lies beyond range."
Secondly, the Commentary includes nibbana (unbinding) within the scope of the All described here — as a dhamma, or object of the intellect — even though there are many other discourses in the Canon specifically stating that nibbana lies beyond the range of the six senses and their objects. Sn 5.6, for instance, indicates that a person who has attained nibbana has gone beyond all phenomena (sabbe dhamma), and therefore cannot be described. MN 49 discusses a "consciousness without feature" (viññanam anidassanam) that does not partake of the "Allness of the All." Furthermore, the following discourse (SN 35.24) says that the "All" is to be abandoned. At no point does the Canon say that nibbana is to be abandoned. Nibbana follows on cessation (nirodha), which is to be realized. Once nibbana is realized, there are no further tasks to be done.
Thus it seems more this discourse's discussion of "All" is meant to limit the use of the word "all" throughout the Buddha's teachings to the six sense spheres and their objects. As the following discourse shows, this would also include the consciousness, contact, and feelings connected with the sense spheres and their objects. Nibbana would lie outside of the word, "all." This would fit in with another point made several times in the Canon: that dispassion is the highest of all dhammas (Iti 90), while the arahant has gone beyond even dispassion (Sn 4.6; Sn 4.10).
This raises the question, if the word "all" does not include nibbana, does that mean that one may infer from the statement, "all phenomena are not-self" that nibbana is self? The answer is no. As AN 4.174 states, to even ask if there is anything remaining or not remaining (or both, or neither) after the cessation of the six sense spheres is to differentiate what is by nature undifferentiated (or to objectify the unobjectified — see the Introduction to MN 18). The range of differentiation goes only as far as the "All." Perceptions of self or not-self, which would count as differentiation, would not apply beyond the "All." When the cessation of the "All" is experienced, all differentiation is allayed.
See also: SN 35.24