Hmm...
I think I recall the old shields reduced incoming damage but added heat or drained energy based on what kind you had. I didn't like that and never used them. I think if remade a similar way they could work. Moderate damage reduction with the the blocked damage converting added heat or drained energy, there is a cap on how much damage it can block, and it only blocks damage directed towards your health, not heat damage or energy drain.
This could help out energy and heat players if enough phys used shields. Since physical is so strong, many palyers would likely use these shields, making it easier for heat players to overheat opponents and energy mechs to drain them. However, if the balance changes Gato Games plan on implementing make everything viable, then it doesn't really matter.