Assuming that the next stormlight chapters will show a conflict with some spren deaths, repeating the Teft's Phendorama death.
This could lead to knight's radiant to follow 3 possible outcomes:
avoiding another bond due the emotional trauma;
bonding a spren of the same order, if they are still aligned with that order values;
bonding a spren of a different order, due to character changes related to their last spren death and their impressions of the ongoing conflict. (my guess for Sigzil)
Don't remenber examples of an "unbonding" of sprens that did'nt result in the spren's death, and I'm wildly guessing Sigzil would be very burdened by guilt if he killed his first spren, so maybe it would be less traumatic to the spren being a casuality of the conflict with the singers.