Who are "Bnei Shikulayich"?
Rashi: Children that you were bereft of them.
What is the meaning of "[Tzar Li ha'Makom] Geshah Li v'Eshevah"?
Rashi: Draw close to another side for me, and I will sit.
Radak: The children that you were bereft of them, so many of them will be amidst you, that each will say to his colleague 'I am cramped. Gesh (go away) for me, so I will be able to sit.
Radak citing Targum Yonasan: Make room for me, and I will sit.
Malbim: The exiles that you were bereft of them, they will tell you "the place is narrow for me. I cannot enter it. Therefore, come close to me, so I can sit amidst you." I.e. there will be so many Yisraelim that the land cannot contain them. Therefore, the land will expand its borders and stretch to Chutz la'Aretz - "Harchivi Mekom Ahalech" (54:2). This is a metaphor, that the land will approach those who dwell outside of it, and they cannot enter it.
