We have some information from the official progression video for HotS 2.0
2:26 "Gold continues to be the main currency acquired by playing games, gaining levels and completing quests. It is primarily used to unlock heroes"
During this statement, we see Valeera being unlocked for 10,000 gold. This is unchanged from how it works now.
1:32 "All current players will have their cumulative experience transferred to this new system without loss"
During this statement, we see an image of level 40 "the lost vikings" merging with a bunch of other heroes of various levels, becoming a level 155 "the lost vikings" player.
Since player level is likely to zoom from the current level cap (20) to the new actual progressed level, there will likely be a plethora of chests unlocked at the time of release of 2.0 - since master skin color variants can come from these chests, it might be better to wait for this event.
4:50 "All current skin color variants are now forge-able as individual items within this new system"
If you want all three color variants and are willing to pay your gold now, go for it. Otherwise, wait for the new system and pay shards to unlock the color variant(s) you want.
From this other video 3:36 "Master skins are no longer a reward for hitting level 10. The master skins can be achieved at any time and they're just normal skins".