Tomato plants are tough. This is a setback, and it will be delayed, but it should survive.

Shade is a good idea. Coddle it; in particular, monitor the soil moisture and make sure it doesn't dry out (at the moment, it doesn't have deep roots to access moisture in the soil lower in the container) -- but don't let it get too soggy, either. Mulch the soil if you haven't already: that helps keep the soil moisture more consistent.

Just don't be surprised when it doesn't do much for a while that you can see; right now it needs to concentrate on re-building its root system.

When the time comes to move it out of the shade, give it mid-day sun only gradually, or the leaves may sunburn. (And a bit of sunburn won't kill it either. Ask me how I know....)

It will experience some shock and might not do much of anything for awhile. You may even see some lower leaves drop off. But tomatoes transplant well and yours is a large plant. Use the same approach as you do when hardening off tomato plants. Slow and easy.

Here is a link that might be useful: Hardening off tomato plants

Injuring the roots during transplanting is one mechanism thought to induce the switch from a tap root to fibrous roots.

Your plant will be fine. When you transplant it, be sure and clip off the lower leaves and bury the stem in the new pot, then your plant will be better than fine, it will develop a stronger root system.

Tomatoes are virtually impossible to kill once they're going. Seriously, as long as you've got a couple inches of green, you can regrow the entire plant. If its got any roots left at all, it'll be fine in a few weeks.

Last year I had a windstorm that knocked one of my container tomatoes over, rolled it around, snapped half the thing in two. I just stuck the broken limbs in some dirt in a bucket, and not only did the limbs survive, they went on to bear fruit the same year. Heck, several of the limbs had tomatoes still on them and not only did they survive, not only did the tomatoes not wither up on them, but they were even GOOD tasting tomatoes at the end.

Basically, nothing short of weed killer or ripping it up by the roots and tossing it on hot asphalt will kill a tomato plant.

Yep - last year I started my plants to early. I ended up cutting off some of the laterals and top growth to keep them from getting to tall and spindly. I stuck the cuttings directly in pots of soil and most of them rooted up and turned into productive plants by the end of the summer.

If they can survive with no roots, they can certainly survive with "pruned" roots.