I would hope so too/ You COULD argue that even amongst big-budget miniseries, doing a one about the big naval battles would be the most expensive, as the use of CGI and practical effects to recreate them would be prohibitive. Every ship would have to be modeled extensively, plus plenty of big explosions, etc. I can imagine lots of greenscreen even during the non-combat parts of the episodes, or stormy days, etc.
That said, there are ways to cut corners too. Like in BoB, have the series follow one ship (perhaps a cruiser or even a destroyer - carriers would be tough to re-create and none exist anymore in a WWII configuration to use for practical filming) and her crew through the war in one or both oceans. There are plenty of biographical books that follow one ship in this manner (the carrier Enterprise was covered in documentary fashion in "Battle 360") and which could potentially be used.
Then again, it comes down to background too. Spielberg's dad was in the Army in WWII (USAAF it seems, a Communications Cheif for a B-25 bomber squadron) so this one would be close to Steven's heart. While Tom Hanks' dad doesn't seem to have served, Tom is known for extensively researching his parts - Jim Lovell was a Navy man but joined in the postwar, so he may not be a proper source for a WWII series.
I for one would love something about naval aviators in WWII - follow a single squadron from activation through to the end of the war, going through pilots, commanders, land assignments and aircraft along the way. Perhaps with this current one done, they'll have learned enough to give something like that justice.