SPOILER ALERT: Read no further if you haven’t watched and still intend to.

Given all of ABC’s other holes to fill — including the cancellation of “Brothers & Sisters” — one would think a durable soldier like “Desperate Housewives” would be the least of the network’s problems.

Still, keeping a soap afloat is always a high-wire act, and heading into its eighth season, “Housewives” appears to be floundering about looking for some new spark.

Desperatehousewives The cast additions this year, alas, did little to help reinvigorate the show, beginning with the over-broad character played by Vanessa Williams. Yet the real misstep involved the gradual dissolution of the marriage between Lynette (Felicity Huffman) and Tom (Doug Savant), which has always been the one real anchor that the show has in that department.

Huffman’s character is often over the top, but the sweet if rather pliable Tom has stuck by her through thick and thin. So the writers had to go through some real contortions to put their relationship at risk, relatively few of them convincing. Moreover, their situation dominated the two-hour finale until the closing minutes, before diving into a subplot involving Gaby (Eva Longoria) that, frankly, doesn’t really do much to lure the audience back, as cliffhangers go, in the fall.

For all its success with serials, ABC has clearly milked the stellar class launched in the mid-2000s for all they’re worth. “Lost” went out on its own terms, but “Grey’s Anatomy” has become increasingly tedious, and now “Housewives” — which has been uneven, but remained good fun — is starting to show serious fault lines as well.

ABC ran a brief promo for its “Charlie’s Angels” revival during the “Housewives” finale, and maybe that — or another one of the network’s newcomers — will help trigger a turnaround. Clearly, something in the 2011 rookies had better. Because having viewed every episode of “Desperate Housewives,” based on the way this season ended finding the motivation to keep that streak alive might just require divine intervention.