Why not just buy the BGA option then? What if there is a BGA equivalent of a Z77 + 3570K? What would be any different? When was the last time you upgraded CPU's on the same motherboard?
In this thread: People finding irrational reasons to fear change.
It's not all that uncommon to upgrade CPUs though I think it's less common than before. A big factor is that socket types have a shorter lifespan. The LGA 775 socket was great for CPU upgrades. Now we get LGA 1156 -> LGA 1155 -> LGA 1150.
5 or 6 pin difference between three non-compatible socket designs? Was that really necessary? Yes, if you only consider Intel's profit margin. Anyway, if it wasn't for the X79 chipset's sub-par features (JMO & not relevant to topic to warrant details), I would already own a SandyBridge-E MB & CPU with the plan of upgrading to a IvyBridge CPU.
I think the repercussions of going to BGA CPUs extends beyond consumer CPU upgrades, quite possibly impacting motherboard (MB) OEMs like Asus, Gigabyte, etc. Why should Intel go through any extra expense to offer socket and BGA versions of "mainstream" CPUs? Clearly from your post, not all build your own PC consumers will balk at buying a BGA CPU+MB combo. Even if AMD continues to offer socketed CPUs, Intel's performance advantage is a powerful incentive for think twice before going to AMD just for a CPU socket. I think it's much more likely that if Intel does go through with the BGA model, we see BGA for "mainstream", and sockets for "extreme" CPUs. Business server clients will want to keep sockets for upgrading, and it leaves something (at a higher profit margin) for individual enthusiasts who prefer socketed CPUs. Using current sockets as an example, thus LGA 1155 = BGA while LGA 2011 = socket.
Under that scenario, MB OEMs must now purchase Intel CPUs for MBs targeted towards a high majority of the PC market. That's on top of whatever is paid for buying/licensing Intel chipsets already. Of course an Intel CPU would need to bought at some point, but it shifts who makes the initial purchase. MB OEMs now have to pay for and manage a CPU inventory as well as the normal MB product inventory. That's not a small issue given price of a CPU in relation to a MB. There's also added risk associated with that new inventory. For example, if the MB OEM doesn't stock enough of say an i7-3770K based motherboards, they lose sales. On the other hand, if they purchase too many, now that OEM is stuck with excess inventory which may require selling at a loss. This is even more challenging because they have to anticipate demand for each CPU+MB pairings with wrong "guesses" resulting in lost sales or excess inventory - problems which don't exist currently. Finally, Intel's CPU profit margin from MB OEM sales gives Intel some degree of additional pricing advantage for its own competing BGA MB+CPU units. Times are tough for MB OEMs as it is without any additional business model pressures which could lead to one or more MB OEMs deciding to leave the consumer retail MB market. Good for Intel, bad for the rest of us. Maybe a bit of a stretch, but not out of the realm of possibility.
Lastly, there's the issue of having to replace BOTH CPU & MB if something goes wrong with your MB OR CPU even if there's nothing wrong with the other. Perhaps not common, but certainly not unheard of for MBs at least needing replacement. If your under warranty, great, but if not you're forced to replace something you don't need to do... all at a higher cost. Great for Intel, not so for the consumer. There's nothing beneficial for the end user with BGA CPUs, but there's a lot of benefit for Intel. AMD's struggles over the past few years are starting to have repercussions. Intel's dominance, both in sales and CPU performance, gives it huge leverage to dictate major changes to the PC market. I doubt this would happen if the situation was similar to when the Athlon was viewed equal to or even superior to Intel's CPUs. I REALLY HOPE AMD somehow manages to right the ship. Consumers can only benefit from strong AMD/Intel and AMD/Nvidia competition.