There is the option of a magnetic oil pan heater, or an epoxy on oil pan heater, and having the trickle charger on low to keep the batteries warmer, both of which help it start better than dead cold, but are by no means a replacement for the block heater.
I would say to replace it, but do as you please, i hate working in the open winter weather, and I am sure you dont either.
99 Chev C3500 6.5L NV4500 14 bolt 2wd 4.10 130K White Ext, Gray Int. RC159.5" WB DRW Chassis Cab with utility box Runs Great, building up
96 GMC C2500HD 6.5L NV4500 14 bolt 2wd 3.73 240K White Ext, Blue Int. ECLB 155.5"WB SRW Pickup runs bad, getting motor right now
95 GMC C2500HD 6.5L NV4500 14 bolt 2wd 4.10 135K White Ext, Grey Int. RC 131.5"WB SRW Pickup with utility box runs strong, yet huffs on 1 hole
95 Chev C3500HD 6.5L NV4500 D80 2wd 5.13 132K White Ext, Grey Int. RC 159.5"WB DRW Chassis Cab with flatbed bad heads, needs motor re-do
94 GMC C2500HD 6.5L 4L80E 14 bolt 2wd 3.73 300K White Ext, Blue Int. Suburban needs engine
91 GMC C1500, 6.2L SM465 10 bolt 2wd 3.42 59K Red Ext, Red Int. RCLB 131.5"WB SRW Pickup needs injectors, oil cooler lines
91 Chev C1500 4.3L 5LM60 10 bolt 2wd 3.42 ??K White Ext, Red Int. RCLB 131.5"WB SRW Pickup needs...alot
98 GMC C3500 5.7L Vortec NV4500 208K down right now, needs head gaskets (dex cool claims another set! )
92 GMC C3500HD 6.5L Turbo NV4500 160K needs exhaust system and oil cooler lines
93 GMC C3500HD 6.5L Turbo 4L80E 260K had a crate 6.5L sometime
All above are 159.5" C&C, 10'-12' flatbed, Summit white, RC, SL trim, 2wd
96 GMC C2500HD SL ECLB 6.5L 5spd 2wd. 215K (sold to dad, ran good for a bit, started missing at idle, had blowby since purchase
84 Pete 362 COE, 300 BCIII RTOO 13 spd Fuller (3 OD ratios, hard to find) Single axle tractor, air seats, cab, suspension, OEM twin 200 gallon tanks.
74 Pete 352 COE, cat, 13spd TS, B&H grain truck
90 Marmon 57P long hood conventional, 60"flattop, 12.7L60 Series, 13 spd fuller, TS tractor
76 Marmon COE 8V92T 13spd fuller, TS B&H grain truck
95 IHC 9600 COE M11, 10 spd, SA tractor.