Just bought x100, x100s announced! Should I return it & wait for x100s?

Think you answered your own query. No firm delivery dates, no surety you will be given one from the first tranche of deliveries, high initial cost/demand, teething troubles .... and so on.

The resale demand for 'old' X100 is not gonna go away or it's value plummet to zero - you will be deprived of images if it's replacement is delayed. How much are those lost images/memories worth?

I doubt you could hire a camera for the period for any less than the value you might lose on reselling the X100 in 4 or 5 months time.