Would exoplanets like those of Kepler-70 possess magnetic fields?
Although it's not proven, I've just read a research paper which provides evidence for the planets having magnetic fields. Assuming that they exist, of course.

The paper is "A tidally destructed massive planet as the progenitor of the two light planets around the SDB star KIC 05807616."

The authors state:


  Considering that the planets have suffered a recent strong tidal deformation with continuous strong tidal force from the central EHB star, and that they are heated by the central star radiation, they are expected to be hot and liquid, and possess a differential rotation. It is very probable that a strong dynamo is operating in each planet, leading to the required magnetic field.


Bear and Soker also calculate the expected time of evaporation for the closer of the two planets, resulting from the star's intense UV radiation. They arrive at a figure of $\approx 10,000,000$ years. However, Kepler-70 has been a B-subdwarf for 18.4 million years (source: Charpinet et al.) and its exoplanets would therefore be at least that old.

They state:


  the expression is highly uncertain, and we might overestimate the evaporation rate.


However, their calculations show that a planetary magnetic field about 10 times as strong as that of Earth is plausible, and would suffice to protect the exoplanet from evaporation. They find this more likely than uncertainty in the aforementioned calculation.


  Our preferred explanation for a low evaporation rate is the existence of a magnetic field ...  More likely we find the possibility that a planetary magnetic field, about 10 times as strong as that of Earth ... will substantially reduce the evaporation rate by holding the ionized gas.