The pace bowler has claimed 309 Test scalps in 71 Test matches with an average of 22.10.
The Australian selection chief Bailey has stated that skipper Cummins will play a "major part" in this winter's Ashes series.
Speculation had been growing that Cummins might sit out due to a persistent back stress problem that remained unresolved.
Earlier indications from team management suggested no final decision had been made regarding Cummins' participation, with the extended contest scheduled to begin on the 21st of November in the WACA.
Bailey expressed that Cummins is "building up" and was "optimistic" about the prospects of participating.
"We're aware that the clock is ticking and there are permutations around that, not just his injury, but other factors as well," the selector added.
"The outlook is good. [We are] really confident that he's going to play a key capacity. Ideally starting in Perth. Should that not happen, we'll reassess."
Previous Setbacks
Cummins was ruled out the ODI and T20 games against both Asian and Trans-Tasman rivals last month after medical tests showed a stress reaction in his back.
He has a history of spinal problems, with flare-ups in several earlier campaigns forcing him out of three Australian summers in a limited period.
He emphasized he would be ""aggressive" and "take risks" in his recovery plan to secure his spot for the Ashes.
The selector indicated that he did not know if the captain had resumed bowling as part of his rehabilitation but acknowledged it was "getting tight" for him to be fit for the opener.
Contingency Plans
Should Cummins not be fit, ex-skipper Smith will lead the side.
All-rounder Cameron Green was withdrawn recently from Australia's squad for their ODI contests against India as a preventive step because of soreness in his side.
He labeled it as a "slight concern and stated that he's scheduled to appear in the Sheffield Shield, so will be "in a good place to resume bowling."
"Extensive planning has gone into creating the schedule for him to be available for the opening match as an batting and bowling option," he elaborated.
"His involvement was limited to the first two ODIs regardless. The way he swings the cricket bat in white-ball cricket, if it causes any delay for another day, we just made the decision to approach this more conservatively."
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