More or less. Same as when I suggested that using masks actually helps. Or banning people from travelling from hot zones helps (two common sense things that WHO categorically denied).
But being more serious and more precise, the closest disease to this has been SARS, and the antibodies remained in infected people for around 3 years. For MERS (another novel coronavirus, the next most similar thing to this), the antibodies were detected for around one year. For human coronaviruses, the antibodies get detected from a few months to a few years after the infection. So, there is plenty to suggest that there will be some immunity.
When WHO is being cautious what they are really saying is that 'there is no definite proof that the antibodies will stay for some time for everyone - cause you know, there has not bee some time since people get infected and healed - and even if that is the case, we do not know for how long they will be effective'. Nevertheless, Chinese studies showed around 70-80% of healed patients had enough antibodies after being healed (though obviously there are still some unknowns). However, with this behaving similar to SARS, I guess it is likely that we will have some immunity after infection, though it might not be for a long time, and almost certainly won't be lifelong immunity.