My understanding is that they increase the sublevel of an ability that is not the one that you are training. This will result in pops similar to what you observe with the ability trained, but obviously, it will take longer. So, to answer your question, I do not think you will lose it. Obviously, with age, all players lose sublevels and levels, but this is not specific to the elastic effect.
That is different from other explanations I have seen. So, if I train 1v1 G, for example, the OD sub level is increasing. When I switch to training OD, that skill will train faster because the sub level has been increasing while training 1v1. That explains why the related skill trains faster, something I have not understood before, if I understand correctly.