Here is Jeffrey Samuels from an old article:
In the Sampasaadaniiyasutta of the Diigha Nikaaya, for instance, Saariputta is professed to have said: "In the presence of the Exalted One have I heard him say and from him have received, that... in times gone by and in future times there have been, and will be other Supreme Buddhas equal to himself [i.e., Gotama] in the matter of Enlightenment." Thus, no longer is the term "bodhisattva" used solely in conjunction with Gotama, with other past buddhas, and with Maitreya; the bodhisattva-yaana is regarded as a possible, albeit difficult, path open to anyone who desires buddhahood.
Why say this if Arahants were all he wanted his Dhamma to produce?
Some more from Ven. Rahula: http://www.buddhanet.net/budsas/ebud/ebdha126.htm