Put it in context. The whole passage is basically saying, "Who are you to question and/or talk back to God?" The "what if" in this context is basically saying "So what if God chooses to let the unrighteous continue in their wicked ways for a time, instead of sending them straight to the destruction that they were prepared for? He's God, and He's allowed to do that!"
You are correct the "what if" precedes a rhetorical question while Hebrews 6:4-6 makes a statement of fact that is far from a rhetorical statement. Also as you posted Paul is saying "what if God chooses to let the unrighteous continue in their wicked ways"; Paul did not write that God willed the unrighteous to continue in their wicked ways", which brings us back to free will.
Now since you want to bring OSAS into this thread if you are willing to address Jesus and Paul's teaching that some will fall away from the faith without posting an opinion like "they were never saved in the first place", we can address OSAS again.
Aineo wrote:
We are also told that God is not willing that any man should perish (2 Peter 3:9)
I've addressed this in other threads, and you've ignored me.
Come on Beads, you have ignored the Scriptures that disprove what you choose to believe; Scriptures that are not rhetorical in nature.
Now lets get back to Romans 9:16-18. Paul writes that God hardened Pharaoh's heart. However, if you actually read the Exodus account where God hardened Pharaoh's heart He did so only
after Moses records that Pharaoh hardened His own heart.
Exodus 8:10-19
10 Then he said, "Tomorrow." So he said, "May it be according to your word, that you may know that there is no one like the LORD our God. 11 And the frogs will depart from you and your houses and your servants and your people; they will be left only in the Nile." 12 Then Moses and Aaron went out from Pharaoh, and Moses cried to the LORD concerning the frogs which He had inflicted upon Pharaoh. 13 And the LORD did according to the word of Moses, and the frogs died out of the houses, the courts, and the fields. 14 So they piled them in heaps, and the land became foul. 15 But when Pharaoh saw that there was relief, he hardened his heart and did not listen to them, as the LORD had said.
16 Then the LORD said to Moses, "Say to Aaron, 'Stretch out your staff and strike the dust of the earth, that it may become gnats through all the land of Egypt.'" 17 And they did so; and Aaron stretched out his hand with his staff, and struck the dust of the earth, and there were gnats on man and beast. All the dust of the earth became gnats through all the land of Egypt. 18 And the magicians tried with their secret arts to bring forth gnats, but they could not; so there were gnats on man and beast. 19 Then the magicians said to Pharaoh, "This is the finger of God." But Pharaoh's heart was hardened, and he did not listen to them, as the LORD had said.
NAS
Exodus 8:30-32
30 So Moses went out from Pharaoh and made supplication to the LORD. 31 And the LORD did as Moses asked, and removed the swarms of insects from Pharaoh, from his servants and from his people; not one remained. 32 But Pharaoh hardened his heart this time also, and he did not let the people go. NAS
It is not until Exodus 10 that God states He will hardern Pharaoh's heart.
Exodus 10:1-2
10:1 Then the LORD said to Moses, "Go to Pharaoh, for I have hardened his heart and the heart of his servants, that I may perform these signs of Mine among them, 2 and that you may tell in the hearing of your son, and of your grandson, how I made a mockery of the Egyptians, and how I performed My signs among them; that you may know that I am the LORD. " NAS