If you lose function of all pitots/ statics sources (including auxiliary/alternates)which is not highly probable,unless you have multiple bird strikes while flying through hail and some nasty mean mechanic taped your static ports after you finished your walk around.. that means your only reference for speed would be pitch/thrust settings (IRS is giving tas)and for altitude...maybe your RA?so below 2500 feet ull get some to look for..
ATC will get the info your transponder is giving them from your selected altimeter data..so only thing they could do is give you vectors to low terrain if possible in VFR conditions..
Please take this with pinch of salt,not an engineer here...just first thoughts of a pilot.
