Depends what you're asking, honestly. The quick and easy version is, yes, they CAN tank and/or heal flashpoints and still leave room for success.
The full truth is somewhat less promising, however. Unless things have changed dramatically since beta, companions will generally do fine tanking or healing in BT or Esseles, though players tend to do better (real intelligence vs AI). By about the second FP though, I found that they weren't really well-suited to tank, (again, mostly due to AI issues. Accidentally pulling pats and such). They may be ok to heal though, depending on how good your group is.