Things that read "target player" will be changed to "target player or planeswalker." E.g., Lava Spike
, Boros Charm
, Kessig Malcontents
. However, if the amount of damage is calculated by using information about that player or objects they control, the text will remain unchanged and can now damage only the player. For example, Sudden Impact
deals damage to a player equal to the number of cards in their hand, and since that text can't apply to planeswalkers (they have no hands—hands of cards, that is), the card will not be able to damage planeswalkers in the future.