Just some WAGs here, but...
Given their number of employees (small, for a 'worldwide' company), their non-exclusive presence / market niche, and obvious lack of access to capital... I'll guess that the IP / brand of the company is the only real asset (company name, any exclusive patents).
I think a buyer would come from the other players in this market - DeWalt, Ridgid, etc., who may have had their own machines made by Shop Vac -? I know Sears did, but they're selling their own assets, not purchasing anyone else's.
Can't hazard a guess as to who the suitor was, but might have been a private equity firm, instead of the other companies -- that would allow Shop Vac to keep operating, more or less as-is, with a new owner 'behind the curtain' (who could get the company back to profitability, then sell it for a net profit on investment.) The company probably had a mountain of debt, given how quickly they ceased operations.
With the closing of the company, buyer(s) will likely be able to purchase the remaining assets at a deep discount to what they were priced at when the company was an ongoing concern. Or, to think of it another way... the vultures can now pick over the carcass, without having to assume any of its debt.
If nothing else, those companies could have a nice secondary market in replacement / consumable parts (filters, hoses/nozzles, etc.) And that could be offshored, of course. Suffice to say... I'd be surprised if any of the 1700 people were picked up, given the state of the economy.
Again... just guesses. I'm not a market analyst.