The whole reason May called this vote was because her existing ranks of MPs were divided as to what was the right approach to Brexit ("hard" versus "soft").  May wanted greater leverage to press for a hard Brexit.
That has utterly collapsed now, because the Tories are trying to rely on DUP, which opposes hard Brexit.  But many of May's MPs view any modification of terms to please DUP as impossible.
So no, this arrangement is not going to last very long.