An el nino by CPC standards is very unlikely. The MAM ONI is -1.1. Since 1950, the only two seasons to go on to qualify as an official el nino during the subsequent cold seasons following a MAM ONI of -0.5 or lower are 1976 and 2018...both merely -0.5 MAM ONI.
They each peaked at +0.9 ONI....still weak. Even a recovery that drastic only takes us to a peak ONI of +0.3, which is warm neutral.
Now, this isn't to say that we absolutely can not pull off an el nino like season, as arbitrary thresholds are not the ultimate determinant.
There a small chance....as in addition to last December, the other extreme -PDO Decembers are 1955, 1964, 2008 and 2010. We would need to pull off a recovery similar to 2009, on the heels of the extreme 12/2008 PDO, which recovered from a MAM 2009 ONI of -0.3 to +1.6 in NDJ. I do not see that, but this kind of PAC reversal would take us back up to a peak of +0.8 ONI for the cold season, which would be weak el nino.