A new motherboard will give you a 'new machine' which will last quite a few more years. I don't think sewing machines are quite like computers where cpu and other chips etc can fail but my daughter needed two replaced in her Janome 11000 within 2 months this year - shop owner said it was caused by "condensation from her evaporative air conditioning and not covered by warranty for second replacement - Fortunately for her, it was covered and she seems quite happy with it now.
Weigh up cost of total replacement with new machine - embroidery machines are fun - Brother do a Disney version of my Innovis 4000D and I like the quality of stitching.