As the tomato is a perennial I'm sure they will flower and produce fruit next year but as for size, quality and quantity that is something that could only be ascertained by experiment. Over winter them and see what the results are. My view is that it is not really worth the effort as the fruit will probably be inferior to those on a first year plant. Also you are inviting the establishment of air and soil diseases in the glasshouse which should be thoroughly cleaned annually and the soil changed every 3 years if a bed and annually if in containers.
If they are growing outdoors I would say the same - remove them, augment the soil with organic matter and next year plant with new tomatoes. Better still plant the new tomatoes in a different part of the plot.