There is potential!
The starbases can be upgraded to a crazy amount of hitpoints (roughly 15,000 off the top of my head, although you must understand they start out weak - around 3000). And there are mines. So all the potential is there.
On the flip-side, I played the latest entrenchment version against the AI last night, and I was blowing fully-upgraded starbases to smithereens with a mid-game fleet. TEC and Advent both get long range anti-structure cruisers which take out starbases. I had about 5 of those TEC torpedo cruisers, and maybe 50 or so bomber strikecraft, and the 15,000 hp Advent starbase not only went down quickly, it didn't even get a chance to fire back (all my stuff was out of its range).
Don't take anything here as definitive, however. 1) this was against the AI, not a person, 2) the AI had no mines, 3) the AI had no repair bays, 4) The ai had no fighters or flak. Also, I can promise you that unit balance is not currently set in stone. From my impression, unit stats are at this point "place-holders."
Starbases could end up being an expensive joke. Or, they could end up being something impressive. Who knows?