I notice that many new multifx pedals now use LCD screens instead of simple LED panels so they can cram more pixels/text into the unit.

My question is, how long can these LCD screens last? I have many LCD based products over the years, many develop problems due to age, and the lcd fluid tend to leak all over the screen.

Are you worried about the LCD screen in your mfx or pedals getting damaged due to age or abuse?

I am considering getting a used Zoom MS-70CDR but the LCD screen kinda worries me.

This is the first time i've seen LCD units used in effects pedals. Previously I use mostly simple LED panel based pedals.
Probably decades. The lamp technology in the displays should be the same used in computer monitors, and those can last over a decade while turned on eight or more hours a day. The foot switches will probably break first.
Will probably last a long time (like backlit LCD watches), but not if abused. I had an MS-50 in a plastic container in a suitcase--the plastic bent and pushed on the LCD screen, which messed up the screen even though it wasn't cracked--turned it black, basically. ZOOM was great about replacing it under warranty. Now I keep a couple old credit cards strapped over the screen with a rubber band when I'm not using it--whether it's on the pedal board or if I'm carrying it around alone in a small Pelican case.

It's such a great pedal I say go for it. No one else makes anything that comes close--from what I hear, the Korg MFX pedal just doesn't cut it.

Never had any problems with the LCDs in my G1onX or my G5.