That depends. By curing the genophage, you lose Salarian support. You do still get a fleet after saving the counciler but you can't predict the future. When you were making that decision, you had to assume that the Salarians wouldn't support you and thus, the Galaxy would stay divided. By sabotaging the genophage, you would get Salarian support AND still have Krogan support. I mean come on, Wrex having another mole in the STG who just happened to find the conversation between Shepard and the Dalatrass was a pretty unlikely event. So basically, at the time that you make this decision, you were choosing between Salarian support + Krogan support or just simply Krogan support. By choosing the cure, you are guaranteed to lose Salarian support. By choosing sabotage, you are NOT guaranteed to lose Krogan support. You get Salarian scientific expertise helping with the crucible and can safely assume that you will have your Krogan ground troops as well.The sabotage really was the more logical choice if your goal was survival at all costs, which is how I like to play my renegades.
And we really can't know for sure that Wrex will maintain stability across all of the Krogan. Even in ME2, we saw that there were Krogan clans that disagreed with Wrex, like the Uvenk and Bloodpack clans. Also, in ME3, we saw Wreav and a few other Krogan that criticized Wrex. There obviously are Krogan out there that disagree with Wrex. My concern isn't that Wrex will betray us but rather that, the clans that oppose him will cause chaos. After all, curing the genophage will boost the numbers of these opposing clans as well (by a great deal).
That's a Fair point, Though Shepard should always consider the possibility of the Krogans finding out, which would be terrible during the war. Also, regardless of the cure choice Shepard might have some STG support (Kirrahe) even before the choice. The fleet is Indeed a loss, but you'd still have the largest fleet of the galaxy at your disposal.
As for the second part, I think there'll be still krogan intelligent enough to recognize the danger of revenge. And the women's clans might help keeping them in check.
If the worst would happen though, salarians would still be alive, and ready to strike them again.