Gautama said that the mindfulness that made up his way of living was something:
… peaceful and choice, something perfect in itself, and a pleasant way of living too.
(SN 54.9, tr. Pali Text Society SN vol V p 285)
In the same chapter, he said:
Before my awakening—when I was still unawakened but intent on awakening—I too usually practiced this kind of meditation.
(SN 54.8)
In the fourth jhana, Gautama exercised his mind to witness many things, including his past habitations and future arisings, and apparently his witness of these things led to the “profound knowledge” or “intuitive wisdom” that cut off the three cankers at the root.
That doesn’t say that everyone who arrives at the fourth concentration is going to experience those things, and the message I take from the passages I’ve quoted above is that even though I haven’t experienced those things, I can still find a way of living that is “peaceful and choice, … perfect in itself”.
Part of the mindfulness that made up Gautama’s was of living was:
[One] trains [oneself], thinking: ‘I will breathe in… breathe out beholding stopping.’
(MN 118, tr. PTS III p 124)
I would argue that he utilized the “survey-sign” taken after the fourth concentration to “behold stopping” breathing in and breathing out, to touch on the fourth concentration as a part of the mindfulness that was his way of living. I would argue that’s in fact what made the other aspects of his mindfulness possible, in a regular rotation.
Although Satipatthana (MN 10) doesn’t mention concentration except in passing (in the factors of enlightenment), the four concentrations culminating in the “stopping” of inhalation and exhalation are included in the mindfulness of Maha Satipatthana (DN 22).
I don’t think that mindfulness is possible without regular attainment of the fourth jhana. If we look at the initial jhanas as indispensable to the mindfulness Gautama recommended (in Anapanasati MN 118 as well), then we have a different perspective on both mindfulness and concentration.
Although I may never witness past habitations and future arisings, and thereby cut off the three cankers as Gautama did, I am satisfied with Gautama’s recommendation of his own mindfulness as a way of living. And enlightenment is not required to practice that mindfulness, as he himself said.