You’re at my lower limit of machine life expectancy with a 12 year old machine, but the i7-3615qm cpu in that machine has a performance passmark score of 5221 - so its still performant enough for now. Wiping the OS & installing Proxmox should breath some longevity into it, but I wouldn’t expect to keep it for more than a sandbox to play with for 1-3 years before replacing with something more modern. Learning to hypervise via proxmox is a useful skill & it’ll make your next setup much better. At least you get a free built in battery backup/screen/keyboard for your node in the meantime lol