I don't understand why people believe caseless munitions is such a substantial improvement to firearms. It's still the same velocities with the same projectiles with minimal alteration to tactical combat. The only advantage is it's lighter which means more rounds which means being able to carry more and longer patrols and lighter load outs. It still occupies the same mass as brass in space or a little less so logistics, on a strategic level, is marginally improved.
Lasers are suspect to diffraction and plasma is only containable in short range. Phasers, from what I understand, are entirely fictional and are just basically particle weapons. Besides questionable wounding efficacy, they all require large amounts of electricity and for some, highly exotic and/or radioactive material.
IMO, the next substantial step is mass accelerators. Gauss and Rail technology. No powder needed. All you have is the bullet of various types and sizes ranging from armour piercing SABOT, regular FMJ, slug, shot , and even grenades. Adjust the muzzle velocity by fiddling with the amount of electric current so you can snipe at full power or lower the current and lob a grenade. Switch to slugs to pop doors or lower the current for hostage or airplane situations to remove the possibility of over penetration. Since you're just carrying the bullet, the amount you can carry on a patrol is way more substantial than caseless munitions and a large amount can be transported on a strategic level. Definitely change infantry tactics as it allows any section member to perform any of our current designations (DMR, grenadier, rifleman, etc) and not be underhanded by situational circumstances (such as an IFV encounter with no anti-armour capability) which allows a more fluid combat environment. Of course, the big problem is still electricity, size, and ruggedness. Mass accelerators still require lots of energy and we currently have nothing of effective size for this. Not to mention that the electric currents of both ideas put large amounts of stress on the metals; fatiguing them easily. A future disadvantage is the proliferation of EMP like weapons to disable soldier systems especially with the whole "net-centric" warfare thinking taking the forefront. Also the velocity of the projectile being launched will be limited due to Newton's Third Law: Every action has an equal and opposite reaction. In other words, too fast and the recoil will launch the user. At least, it'll provide a better transition state than energy weapons since we already know what bullets do.
TL;DR: Science Fiction, Science, Fiction, Science Fiction.
