I've been looking to see whether my 3.5e sorcerer characters could be moved across to 5e, and it turns out to be quite difficult because a number of spells which were important to them are no longer on the sorcerer spell list!
I can see that they have given the sorcerer some of the damaging spells from other class lists (e.g. firestorm), but find it rather odd if they are supposed to only concentrate on being blasters. Without Magic Circle my demonologist sorcerer is a bit stuck, for instance!
Losing the possibility of Shapechange is a bit of a blow for future plans too.
What are poor sorcerers to do? Is there particular rhyme and reason for these changes that you can see?
Part of what is happening here is that sorcerers are more concentrated on their story.
The story of a sorcerer is that they have
innate magic in their blood. That leads to spontaneous, fluid magic. X-men mutant powers.
It does not lead one to being able to draw magic circles to imprison fiends. Drawing that circle is a precise, controlled ritual -- more in the wizard's wheelhouse or the warlock's.
If the important bit about your sorcerer was that he could summon demons, go warlock or wizard, and summon demons.
If the important bit about your sorcerer was that he had magic in his blood, maybe just take a little dip into Ritual Caster in a multiclass at some point to get the demon-summoning abilities.
Sorcerers are not just an alternate spellcasting mechanic now. They have their own narrative, their own identity, their own mechanically implemented design scheme. Don't just be a sorcerer because you want spontaneous magic. Be a sorcerer because you want fluid, flexible, untrained, raw, blood-magic. If that wasn't the important bit of your character, don't be afraid to swap them out for some other class.