Wouldn't it be more advisable to wait for Windows 10 RETAIL version as Windows 10 will be the last major OS release?

My pc is running ahem version and I was thinking of getting a cheap W7/W8 OEM license for this Windows 10 upgrade. But as you know, OEM version is tied to the hardware, specifically the motherboard so you won't be able to reactivate your Windows should you upgrade the mobo. As with most pc enthusiasts, we upgrade our motherboards from time to time and this makes sense if we actually purchase the RETAIL version instead so that we can keep upgrading our hardware without limit. And because Windows 10 is going to be the last OS, it would be endless....as long as Microsoft survives

But does getting a retail W7/8 guarantee you'll get a retail version of Windows 10 ?

Chrome uses Ram like hell. It could easily eat up like 1-2GB Ram..