Unfortunately, all models in the current mac mini line have the same (lack of) upgradeability and accessibility. For example, every different configuration of the new mac mini has it's own specific logic board (motherboard) part number, with different part numbers differentiating 8GB and 16GB models (all other specs identical). In fact, it appears there are 9 different logic boards for the new mini's based on which CPU and memory combination is chosen at time of purchase. Also, the "non-removable" bottom cover is stated to be used across all models in the mac mini lineup.