This announcement from Prusa is fantastic. My MK3S+ works great but at some point I’ll probably do the 3.5 of 3.9 upgrade option:
Original Prusa MK4 is here: Always perfect first layer, high-speed printing with Input shaper, 32-bit platform, Nextruder, MMU3. SHIPPING NOW! - Original Prusa 3D Printers https://blog.prusa3d.com/announcing-original-prusa-mk4_76585/