This might have made sense back in 2001 as Sony had their ultra-portable line and I think some had processors with dynamic clocking but they were very expensive. Apple didn't introduce the Macbook Air until 2008.
Apple's designers seem to respect Sony's design style. Jony Ive asked one of their internal designers to mockup what an iPhone would look like if it was made by Sony:
That looked like the iPhone 4 back in 2006. Sony doesn't design things that look that nice though. This is Sony's version:
They got the power button right and it uses front and back glass but it also came after the iPhone:
Sony Bravia TVs were once seen as the best TVs but they started outsourcing the build of them to Samsung so they get killed in the margins. When it comes to a TV, why pay so much for Sony if you can get a TV built by the same company Samsung for a fraction of the price? The problem with Samsung is that they make great components. Their SSDs are best in class, their display panels are good too. Apple uses Samsung SSDs in the Mac line and Samsung displays in the Retina MBPs. Their Toshiba SSDs had problems and lower speed, their LG panels in the rMBP had the ghosting and burn-in issues. They used Sony batteries in their laptops:
Would a partnership have meant they'd let Sony run iOS on their phones and tablets? Sooner or later the need for each company to make money would drive them apart. It could have meant Sony bringing their Playstation franchise to iOS, maybe dualshock controllers but Sony would ultimately have to make a profit somewhere.
They are selling their PC line to an investment company, spinning off TVs to another company, laying off 5000 people (they have ~145,000 employees) and made $1.1b loss last year:
In the last quarter, they made:
Cameras - $115m
Games - $172m
Mobile and computers - loss of $120m
TVs - $61m
Components, batteries, image sensors, media - loss of $226m
Movies and distribution - $231m
Music - $207m
Financial Services (Sony Bank) - $455m
They seem to be doing ok in a lot of areas and have a decent amount of assets and cash. It makes sense why they'd make lenses for the iPhone because they can't shift their own mobile devices. I think it would be quite good if they brought their PS1 / PS2 / PS3 library to iOS with the dualshock controller. They have game streaming tech now so it doesn't have to be native but Apple would still have to approve it as it would technically be a 3rd party store (even though Netflix is a 3rd party store too and that's on iOS). A little restructuring and focusing on their profit-making activities should set them on the right track.