Re: Only 32-bit, WTF?
Do you need >4GB of memory in the server, or >4GB of memory immediately and simply accessible to each application? They are different things.
If 4GB per application is sufficient, all you need do is find an ARM design partner and motivate them to make you a 32bit ARM chip with a >32bit total address space and document how to use it.
Not rocket science, been going on for decades with other chips (PDP11 16bit core, 22 bit memory address space in some models, accessed via an MMU eg PLAS directives in the OS, x86 had PAE, 32bit core with >32bit memory address space accessed via an MMU, yea even unto the Z80 and some vendors with bank switching magick, and so on).
Or wait a little while till the true 64bit address ARM stuff comes along, but bear in mind that in a design focused on low power consumption and low cost, making addresses twice as wide will likely come with a bit of a penalty in terms of power or performance or both (and hence also cost). Double the width of addresses and the same amount of cache only holds half as many items. Double the width of addresses and there's a far chance that any given application gets bigger. Decisions, decisions.
It's 20 years or so since the first mainstream (albeit non-x86) 64bit chips arrived, with 64bit OSes to boot. But there's still plenty of 32bit-compatible work around. And there's genuined 64bit stuff too. And a grey area in between where "bank switching" may work.
Have a lot of fun, whichever way works best for you.